Thanks everybody for joining me today. I'm going to talk about which balancing product needs with open source objectives. A lot of us find ourselves balancing product needs with open source project objectives to be challenging. And if you do like me, if you do, you're not alone. A lot of us at times when we are working for companies that we have a product time to market needs and then we are looking to see we also want to contribute and make our product part of the any open source project. I'm going to be speaking with the Linux kernel because that's the open source project I'm most familiar with. And then I'm going to share my experiences having to balance product needs in my previous roles at a couple of other companies and with the Linux kernel project objectives. Now we're getting open source and corporate cultural differences and then objectives and goals as well. These roles have different goals and different objectives. That's what makes it challenging in a lot of different ways. It's a delicate balance very often. It is easier to work exclusively on either side of this divide. Like I do currently, I don't work for an organization that has a product. So my focus currently can be easier in some ways being just upstream focus. And then fast when I worked for companies that have products based on Linux kernel. At that point I had to learn to balance balance the needs of the product that I am working on, and as well as what would be beneficial to the company. So that's kind of what we are going to talk about a lot of the lot of what I'm going to share is coming from my experience doing this. I require a lot of delicate finesse and skill to know which hat you want to wear when you are you representing at any point in time. Are you representing the product teams, or are you representing the upstream. And also keeping in mind that you are looking to be productive in your both roles and bring value to both sides.  And also balancing. What does it really mean to do the balancing act, and then how do you, the best practices and how can you bridge between two worlds. Some of you might know upstream releases are time based, not feature based. So that I find is the big difference between the two worlds that causes a lot of the challenges or leads to a lot of challenges. When I say upstream is releases are time based and not feature based meaning what do I mean by that. So Linux kernel releases come out once every eight to 10 weeks and each release has a two week merge window for new features. The Linux kernel development is a continuous development model where development is happening while integration is happening, meaning developers are getting ready for the next release, while we are integrating the features that came into them through the two weeks merge window, right, the two weeks merge window. There's a six to eight weeks of fixing bugs and regressions and integrating all these new features with existing kernel base code base. So all of while all of that is happening, people are planning for future releases. So that is a continuous development model. Like maybe in a product world that you might go through a period of design and development and then and then you add those features and then integrate. So, while a separate group of people might be working on older releases. And then at the same and also, when in a product world when you are thinking about next release you are deciding the features first we are saying okay. Our next release will have this this feature this feature a feature be featured see and you're working towards that, whereas upstream releases are time based if a feature is not ready to make the cut for the merge window, then that feature will be will be in the next release which will come three months from now. So that's the big difference. So another thing to keep in mind is all fixes must go into mainline first right. So we'll talk a little bit about the stable releases and on the next slide. So you can find a lot of the information I'm about working with the kernel development community in the kernel documentation. I'm leaving you with a link here to read. So the development process that we use in upstream kind of also leads to the mindset of upstream developers. We are more focused on whether a feature is not ready or not. The time for merge window calls. So we know that if the feature is not ready, it can go into the next release, and we'll have more time to to make changes to it. So that's the mindset we are working with. And we're also working with the mindset that fixes going into the main line. Get applied to stable release. So we are thinking about, well, if we fix, we have a fix do we can we fix is okay fixes can go in at any time into the mainline right, but they have to go into the mainline first. And then some of the we select fixes for selection of fixes for stables is automated, automated, and then they get selected automatically. We attempt to apply these fixes automatically first. And if the auto apply fails, porting is requested. And at times though, the auto automated tools do find a good chunk of fixes. However, manual selection is also necessary to have the fixes going to status and can be marked for fixes can also be marked for stable releases with the stable tax. You can see all about everything you want to know about in this document document on the in the kernel get everything you ever wanted to know about less stable releases. You can check that and see how that works. So continuing on the upstream mindset. We some stable releases are all tagged for long term as well. So long term updates. stable releases get fixes and security updates and so on. Still keeping in mind all the fixes first go into the mainline, which is when I say mainline. This is the Linux's master get upstream. The point to keep in mind is, if you are a product, if you are trying to balance product needs with upstream needs, you want to keep in mind that upstream developers community might not know about your product needs and might not care about your product needs. Your deadlines or time to market needs or features even upstream cares about features that add value. And they upstream community will be reluctant to take features that aren't ready, meaning you might have a deadline saying I need to get this in by this June 2021 for example, but however, if it's not ready, it won't make it into, if the upstream community doesn't think it's ready, it won't make it into the release. So we have to keep that in mind definitely as you are doing this balancing act of upstream and product. So a few things at this, any questions. Do we have any questions. I don't see any so far but just a reminder you can add them here in the Q&A box at the bottom of your screen or feel free to raise your hand and we can unmute you if you'd like to ask a question live. Great. So what does it mean when you are thinking about product and you're thinking okay I have this design. I want to have these features in my product by this time. So do your homework. That's really important. Research related upstream features. So this, all of the things that I'm talking about aren't necessarily applicable, just don't just apply to product development balancing. It's these are true for anybody that's wanting to contribute. It's just that if you are also responsible for a product that adds more challenges. So anytime you have an idea, research related upstream features, and that is a very important first step, you might find that there is a feature that you can leverage, or there is the end and also enhance that existing feature as opposed to writing and reinventing the wheel, right. Don't want to reinvent the wheel. Leveraging and enhancing existing features benefits everybody that is dependent on that feature or using that feature currently. When a new feature, when you think of an idea for a new feature, make sure that that is works well within the existing framework as well. It is important to design new features to work with the existing framework. For example, you might have you might be adding a different feature potentially, then you will have to work within the framework to see how best you can make that architecture dependent feature fit into the rest of the kernel infrastructure, because the kernel kernel supports 33 plus architectures. So the kernel has generic areas that it is very well partitioned in terms of architecture dependent code and architecture independent code. And when you're adding a new feature that might have might support a new hardware, you'll have to think about how well it works on all architectures. Especially drivers, does the driver is, does it have architectural specific components, or a subsystem might architecture independent. You have to kind of look at that and then see how well it fits into the kernel existing kernel infrastructure and framework. So more on doing your homework. Ask yourself very often, why are you making this change. And this is important to even just explain to the upstream community, what you're doing. And this is important. Also because of the remote nature of the development. You have to explain that in your patch documentation that goes along with the patch. And when you are explaining what a single patch does what and then also if it involves more than one patch what the patch series does if you are proposing changes to the existing feature. You have to make sure that you are not in any way, regressing that feature. If you are proposing a new feature, like I said, earlier, you have to think about how it fits into the rest of the kernel existing features and how it interacts with other features. The challenge. If you are an independent contributor are focusing just on upstream, you don't as much need to worry about time constraints right.  Okay, I want to make this right. I want to contribute something that everybody agrees upon and then, and you have the luxury to take your time. However, when you are working, working to get a release out product release out. You, you have other time constraints. If you are planning, you have to think about it and keep the releases kernel releases in mind, be in sync with those to see how best you can plan. And if you are, you also have to plan based on all the questions you already asked yourself. If you are proposing a changes to an existing feature that might be easier time wise, it might take less time for that to be accepted by that stream community. If it's a new feature it might take longer. If it is a new driver that is independent of. If you have interactions or impact on other modules. It might be easier again. So you have that all requires planning. Think about that and then plan. Also keeping keeping in mind at the same time that benefits of upstreaming your code comes in later in the form of collaboration, you. You are recruiting the rest of the community to help with making enhancements and then also testing, you're leveraging a lot of the extended talent out there. So you have to keep that in mind as well. What, what's in it for you from that angle. So when, when you are thinking about contributing also keeping your extreme upstream hat on, you look at is the solution and feature generic enough for upstream. How does your work help upstream? Does it add new functionality? Does it improve performance or security? Does it harden the code base? And, and so on. Is there a bad, is there a important question to ask is, is there a better way to do what you are setting up today? Would you take this solution? Another important question to ask is, would you take the solution as an upstream developer if somebody else proposes it? Any questions? This is another time I can take some questions. No questions. Yes. Okay. So, what does it mean. So when you have your product hat on. There's some one of the reasons you would reach out to make changes to the upstream set up to make changes to the upstream. You would make changes because upstream doesn't work on your platform. Hardware firmware deviates from a standard say you have to do things a little bit differently. You're, I mean your product hardware. New feature or enhancements on an existing one anchors your product. That means it's very important to your product. So, another, with all of this keeping all of these in mind, can you also decide also have to think about, can you talk about your hardware firmware differences? Can you share? What can you share freely what you cannot share? Can I share or discuss? It's also, it's very important to, from both sides, you don't want to share something that you don't want to share. You want to, it is important also to share so that your solution is accepted. You have to walk the fine line of sharing what's necessary and and not giving the story away. You have to find a way to discuss the details in a generic way. So now comes. So, and all of this brings us to the balancing act. So, a couple of things to keep in mind that upstream. Don't if you expect upstream to take your solution as is, then you are setting yourself up for disappointment. It's not a guarantee at all. It's very often even a small patch would require even when you send a small patch in, expect that somebody might come up with a different way of doing things or point out something that you haven't thought about. So keep that in mind. For proposing a enhancement to an existing feature or a new feature. It is a good idea to discuss the, what you're planning to do at with upstream at conferences. That's probably one of the proposal conference talk and talk about it and see what how well upstream reacts to it. So that's that gives you a good indicator on what you need to change upfront or what you would be doing. So whether your solution will work as these are the refinements you have to make or changes you have to make. You might get a feel for that by discussing early on. Another thing to keep in mind is collaborating and sharing early sharing collaborating and sharing early at conferences and sharing ideas and discussing. It will is is going to make it easier for your feature to be the time for accepting time can be shoulder depending on depending on the refinements you need to make right. So it's always beneficial to collaborate start collaboration and sharing early. Another thing that would benefit the product is adapting it might or might not be possible. However, it would be beneficial to adapt upstream first rule, meaning upstreaming. Having the feature upstream first and then getting it into the product. That will that will be beneficial long run. So you don't have to to go out with a different solution than the one that upstream accepts and then you have, you might end up changing two different core basis or you might end up changing the product after its release to update it with the version that upstream has accepted. So it might be difficult to do later on. It is also important to keep upstream variations to a small percentage. You, this could happen in as you might even if you started upstream first, as you are fixing bugs, or as you are finding problems that needed to be fixed. If you don't keep up with the upstream, it might become difficult to keep them in sync. So you have to this, you have to first decide how often to merge upstream because merging upstream. You have to validate your product, of course, right, because upstream brings changes. It changes that could impact your product support. So you have to to figure out or decide what's the optimal merge points are for your upstream and frequent is better. So that's the best solution to do because, because upstream yours, you might see some regressions but you're also seeing improvements right continuous security updates continuous fixes. So upstream, keeping up with upstream and merging frequently is necessary to further health of the product. So you have to keep track of with that in mind you have to keep track of stable and long term releases to to to two different things. So many products release many products choose a long term release as their base for release, and then they keep taking on security updates as new stables come in fixes. They keep moving to the recent table as latest table release for that long term release. So you, this is all again, you have to kind of decide what happens if you don't hit that target, what happens contingency plan, if it doesn't, and then if the contingency plan is release and then you're out of upstream then you're balancing the act of what if you're the your feature doesn't make it as you expected in the same shape or form into upstream so you might have to make changes to product, as well as upstream. Let's talk a little bit about bridging between the two words, explaining. So you as a upstream developer that's also focused on product development. If you are straddling those two words. Then you are doing two things. One is you are explaining upstream to product teams, and you are telling them the benefits and importance of offering first and paying it forward for benefits and of collaboration with upstream and keeping the delta, the importance of keeping the delta from upstream small. You're also asking them to plan. You are talking to them about planning ahead, and then also bringing that into your product teams that knowledge into your product teams, and then explaining your feature or change to the upstream community. You are talking to them upstream community working with them to to meet your product needs. You are making you are working to get you get the features that support your product by the upstream community you want that content in the upstream So you are continuously talking communicating what's in it for you message to both sides. So let's let's talk about we have talked a lot about balancing both worlds and then challenges. Now let's talk about a few things to keep in mind. These would be helpful. Not just for people that are balancing product and then needs and upstream community needs are straddling that fence of upstream and product. This is beneficial to everybody that is contributing to to upstream open source projects. So be open to changing your solution or your idea. When you propose a your idea or a solution assume that will change and evolve. Don't be locked into your I first idea, you know, it will change. Be mindful of adding value to both worlds. You know, you want to get your product out you want to get, or you want to see a feature that you are using maybe perhaps for your in your, even if it's not a product you're just using that feature. You want to contribute think about adding, helping yourself and helping others right so. So that will go along with before getting your work accepted into the by the community. Be open to be a student and teacher at the same time, because there is a lot to learn from the community that and then you that this is a this is a collaborative community with the trust trust and respect. So leveraging this collective expertise of the community is going to be beneficial for the project Linux kernel as well as the rest of the community as well. So also adopting the attitude that I don't know everything is going to help in the long run to to be able to contribute to the computer and work with the community. So finally, I'm going to leave you with a few thoughts. Learn as you go. I find myself learning every day and keep learning. And there is really no textbook that teaches these skills, just have to, to make mistakes, learn from your mistakes, and then learn the balancing act. It's a perfect solution for every product and every scenario. Keeping the some of these upstream mindset in mind will help make the balancing act easier. Do you not but just again as a reminder to anyone who's joined us recently you are able to either add a question into the Q&A box at the bottom of your screen, or you can raise your hand and I can alert Shua that you have a question or you can also just unmute yourself at any time that feel free to ask a question or provide any comments, welcome your participation. So you are welcome to share your thoughts as well. If you don't have any questions. If not, we can wrap this up. We did get a comment Daniel said very thought provoking thank you. Just want to give it a few more moments. Alright, looks like we have a question from the comment. If a Linux kernel maintainer is employed by a company now how does the community keep him in check that he isn't doing anything in a hurry because of his company's pressure. That is a very good question. So, community doesn't have to necessarily keep a maintainer in check. It is all trust and respect right maintainer as a maintainer, even if you are not a maintainer. If you're an active contributor. If you're constantly balancing is it is very important for maintainers to not lose their credibility. If a maintainer doesn't do that balancing act of keeping it to both worlds, thinking about both upstream value to upstream and value to product. And if they are only thinking about the product. They end up losing credibility in the community. So they become not very effective. So that in itself is acts as a check. And it will help, but I mean, obviously there are ways you can if they if there is a you see a pattern if you see a pattern that a maintainer might be abusing trust the community and other developers are placing, then there are, there will be consequences of course right not not consequence in terms of in terms of consequences will be in terms of losing credibility so none of us really want to do that we want to be part of the community. So does that answer your question. We'll give him a few moments to respond if you'd like but we did get two more questions in. Okay. Oh Mohammed said yes it does thank you. And so another question we got from Armstrong said thanks for the talk. What happens to changes like bug fixes new features etc, that are not integrated into future releases. Haven't been accepted into the by the maintainers. Is that the question, because most fixes. Well, I mean, fixes do get accepted but are you talking about the ones that don't get a few moments to respond. Yes, those that are accepted, he said. So, so I will answer the question in two different ways. So, say, if you were a fixed came in and that isn't accepted. What about the problem being fixed in a different way that's one answer to that. If it's still an outstanding problem, then the submit submit or pass submit or can recent the patch and say hey this is still a problem. And then, if it is a stable release, and there is a fix upstream that hasn't been selected by auto fixes auto tools that select fixes, or any manual method methods, then that fix can be sent to upstream, sent to stable. So, I think a mainline commit ID in the stable, the patch commit log saying, Hey, this fixes already in upstream. It's not in this stable release, you can do that. The third possibility, possibly is that your product has, you have been fixing bugs in the product. That's where the keeping the delta small comes in. So if you do not upstream the bugs that you're finding in your product, or as your feature that you already upstreamed, then you are accumulating a lot of debt. So you want to keep that delta small. So that is three different aspects of the question you asked. If that's not what you have in mind, please ask another question in the follow up question. Great, we have one more question from Tito. They asked, what advice would you have for students interested in becoming a Colonel developer maintainer. They, we have, we have a lot has mentorship programs will, this is probably a good time to talk about that. So we have mentorship program that's designed to help new developers for this with necessary skills and resources to experiment learn and contribute effectively to open source communities. So there are other resources available, like the webinars we are doing, of course, and then you can join the Cardinal newbies and check Cardinal newbies website as well as IRC. So what I would say is that the best way to get started is you have multiple ways to get started. You can at the beginning, if you if you have never used Linux Cardinal, and if you haven't really played with it on your hardware. The first thing to do is go and start taking beginner classes available. Elef training has a class. I did a class for a couple of years ago, primarily to help mentees from in the mentorship program to get started as as a screening and also helping developers that want to be in a unstructured learning self study. It's Linux beginners guide for Linux Cardinal development, you can do that. You can start that offers a lot of tips, and then test stable releases, and then other Cardinal releases as they're coming in. That is one of the best ways to to learn and then also find problems so you can either report the problems you can take the time to fix the bugs. And another option is run tools, automated tools, come, um, compiling Cardinals with warnings turned out turned up and then you might find problems that way.  We don't have any other further questions. We want to just give it a few more moments in case anyone has anything else. Would you like to go ahead and show or we would you like to say on for Well, we can wrap up. Yeah. Okay, well, thank you for your time today and thank you to all of the participants who joined us. As a reminder this recording will be on the Linux Foundation YouTube page later today and we will also be sharing the slides on our website. We hope you're able to join us for future mentorship sessions. Thank you and have a wonderful day. Thank you.


Hi. I'm terribly sorry to get between you and some beer, so I will try and keep this short. So quite often when I give these talks, I do talks about futures and all the cool features that are coming in later versions of Postgres. I've decided to do something else today because we've got a couple of product announcements that we're happy to make at this conference. So there's going to be some announcement emails coming out as well, but I just wanted to explain briefly what those product announcements were and then just explain how that fits into some of the other things that we do as well. So everything you see here is all fully open source and where appropriate is in progress being submitted through to Postgres Core. So let's go straight on to the first one is PG Loader. I'm sure that some of you have seen Dimitri's presentations about PG Loader. You should be aware by now that we're now at version 3.2 of PG Loader. So Dimitri's had a lot of experience at making the load utility very flexible and this particular release is the point where he's managed to finally crack parallel data loading and that's why the slide says that it's up to 10 times faster. Originally he wrote it in Python and there were some problems with the global lock that meant that we couldn't get the parallelism to work properly. So as of now PG Loader is an extremely fast load utility and it's got so many different formats and options that I'm not even going to try to list them for you, but it's extremely flexible load utility. What Dimitri's been working on in the background is that PG Loader also does completely automated conversion of MySQL and SQL Lite databases. So you literally just give it a logon to the MySQL system and say convert it and it will connect to Postgres, connect to MySQL, it will copy across all of the DDL including intelligent transforms and then it will load all of the data across as well. So we're talking about a single command line to convert whole databases and so this is not just a data load tool, it's actually a migration tool that's also particularly important. When you look at the number of databases that we see in modern enterprises if you think that the average database was going to take a month of manual labour to edit things you can see that we would just never ever get adoption rates up there but with this kind of approach we're actually going to take, rather than taking it a month, we're taking as long as it takes to type the commands to do the migration. So given that 90% of databases are around a gigabyte in size this is firmly aimed at converting the vast majority of databases even if it doesn't convert the big complex databases. So the next thing to talk about is Barman, which is the backup and recovery manager for Postgres. Version 1.4 was released last month and supports 9.4. It fully supports multiple servers with multiple backups and configurable policy management to allow you to specify your backups and of course does full point-in-time recovery when and if you need it so you can easily test what's going on. This version now does file level incremental backup which is very important for larger installs. We've also got features there to do the backup from standby nodes as well as full compression. So Gabrielle is doing a talk tomorrow at noon to give the full details on Barman so this is me just announcing this as part of the other announcements really not to steal his thunder. So tomorrow at noon. And the next one is Rep Manager. Rep Manager version 3 is now tagged and ready for announcement. Version 3 because we've completely redesigned the earlier versions to take into account the later capabilities of Postgres 9.4. So there is a version of Rep Manager called version 2.02 which supports 9.4 but that version doesn't support all of the features. Rep Manager version 3.0 supports 9.3 onwards. So for those releases we have full support for things like cascading, replication slots and you have a choice of whether to use PG base backup or rsync depending on how your systems are configured. This version also provides fully automated failover including a witness server so it allows you to manage quite complex installs so it's specifically designed to manage more than two nodes in that config. So that's released today. It's just not announced on the public mailing lists yet. Next thing to talk about is of course the BDR project. Some of you have already heard details about that. There's a full talk by Andres tomorrow afternoon at 3 o'clock going into details of that project. The project itself, just in brief, is the next generation replication project. We've already been going at this point on the BDR project for three years so a lot of the features that are in 9.3 or 9.4 have actually come from the BDR project already. It's fully open source and we've designed it as a submission to Core PostgreSQL so every single aspect of this project is being submitted to Core. That doesn't mean it's automatically accepted by Core so there's been a lot of redesign work and internal reworking to get it to an acceptable form. The emphasis that we've placed on this project throughout its development is that we're aiming to not only make it a submission to Core PostgreSQL so that in the future these features will be available to all the point is that it's working code now. So for the people that need these features we've actually got versions that you can make use of right now. So BDR comes in two separate variants. The first variant is something that we're calling unidirectional replication or UDR and the variant that we have here is it's PostgreSQL 9.4 plus an extension so it takes stock PostgreSQL, you just plug an extension into it and it will use the logical decoding feature that we have in 9.4 and when you put those two things together you get that holy grail that we've been talking about for some time which is logical replication. Now at 9.4 that is data only we are not replicating DDL or sequences yet in 9.4 but those two operations are in full swing to make it into 9.5 I'm not going to prejudge that situation but if all goes to plan we'll get all three of those things working in 9.5. Now the plug-in itself we're hoping will be accepted by Core in 9.6 but of course that is yet for discussion as well. So what does UDR provide? Well the first feature is it provides zero downtime upgrade now that's not very useful because it allows you to upgrade from 9.4 to a later release and obviously there isn't a later release yet but it works so cool but the main thing is we like to plan ahead so the second feature that a lot of people have been looking forward to is something that we call selective replication and that's the idea that you can specify particular tables that you would like to replicate rather than the whole database and what we've implemented is we've taken the concept from slony known as replication sets and implemented exactly that concept into UDR so that you can specify particular tables to be moved across to other nodes. There's a great future for that way of doing things in the sense that what we have already implemented as well is the ability to select particular types of operation that you wish to replicate for example to replicate inserts but not deletes which allows you to feed a data warehouse with changes from your operational system. So UDR is an extension that works now as part of the 0.9 release of the BDR project. The second variant that we support in BDR is what we refer to as full BDR or just BDR and that's where we have a modified version of the Postgres server working with the extension and obviously modified version of Postgres server sounds like fork but that is not going to happen. What we have is code that's fully open source, all submitted to core and a lot of it is actually already in 9.5 but there's still many things to go yet. The full plan is to allow very large clusters up to 48 nodes is what we've talked about in terms of support but we have already tested higher numbers of nodes for working together. The design that we've gone for is a fully interconnected mesh of nodes and we are replicating everything. So we're replicating the data changes, we're replicating the DDL and we're replicating or I should say we're not directly replicating sequences but sequences work in a global manner so that the IDs that are allocated from a sequence never cause duplicate entries on multiple nodes. So this is full multi-master and we are hoping that this will eventually get into Postgres core but please be aware that that could be 9.5, 9.6, 9.7 even if there is going to be one. So in terms of this making it into core Postgres we could be looking at possibly as many as four years from now before it's a done deal part of core. Because we understand that baking good software takes time the idea is that we're releasing it for your use now rather than sit and talk about it for another four years. So overall by the time all of it gets in that could be a project of up to seven years in duration bearing in mind that we've already done three years on this project. So let me just mention one last thing about that is that we've got as of now four people working pretty much full time on the code writing the manuals, we've got people working full time on QA and because there's a number of variants we've got quite a lot of testing to do quite a lot of feature development but all of this is also available on multiple platforms in binary form so we've got Debian installers, RPMs, it works on free BSD so there's a lot of attention being paid to the capability to run on multiple platforms so it's not just the sources available this is actually available in a practical usable form. So while I have been highlighting these additional products or additional tools that you can use with Postgres I just wanted to also say that we do spend a lot of time and attention on features for core Postgres as well these aren't things that we've released as separate products they're just things that we're submitting directly into core some of them go in quite quietly there's a couple of things that are my favourites there such as locked row identification previously when you got lock weights in your application it used to just say there is a lock and you sort of think well that's nice now what do I do and actually we spent some time looking into the detail of that worked out how to pick out the particular detail of which row had been locked and now if you get that error message in the log you can actually do something in your application to improve things so there's some big features there like the lock scalability for example but there's also some very small features where we're paying attention to the level of detail that you need as application developers in order to use the Postgres system so all of this work is fully open source and explaining it to you now both to highlight the features of the new release and also to explain that if you do work with second quadrant you can see exactly what we're doing with the money is putting that back into releasing open source code for everybody to use so be a time


Okay, and I apologize that the title of my talk has changed, but that's my fault. Because I've just recently visited Clemens Poupe in Karlsruhe. And we did significant progress on this paper and had great fun. And I think that our perspective on the whole thing has changed. So we will be talking, I will be talking about Condorcet domains. So first, what's Condorcet paradox? So everybody knows what important figure in French Revolution Condorcet was. And how important he was as a scientist. He was first to try to apply probability theory to social choice. Well, he noticed that sometimes majority relation can be intransitive. For, there are two situations here. We have three persons, three alternatives. So three persons choosing among three alternatives. And they have preferences, A preferred to B preferred to C, B preferred to C preferred to A, C preferred to A to B. So these are cyclic preferences and majority relations behave badly. For example, if you ask them to compare A and B, two of them will vote for A, first and third. So A will win. And if you ask them to compare B and C, then first and second will vote for B. So B will win over C. And if you ask them to compare C and A, two of them will vote for C. And so C wins over A. So majority relation is intransitive. You cannot decide what's better for this society. Okay, so, and this is a similar situation. So what is a condorsed domain? So you can try, you can think of finding a condorsed domain is kind of agreement in society. So to avoid coordination, certain coordination to avoid undesirable outcomes so that majority can take intransitive decisions. For example, you can, and of course you have to prohibit one of these orders and one of these orders. At least two orders you have to prohibit to get transitive majority. So for example, you can choose these four linear orders and society can agree on using only these. Or you can choose these four orders. So the difference between them is not quite clear from this, but if we put it on a permutahedron, what is permutahedron? Permutahedron, that's a polytope whose vertices are linear orders or elements of symmetric group if you are an algebraic, has an algebraic background. So and in this polytope, polytope edges are drawn between any pair of orders which differ by a single switch. For example, here you switch from A and B. That's a single switch and they are neighbors in the permutahedron. So the first domain was graphically described by the domain D1 graphically described like this. So it is connected in this graph and the second is disconnected. So and in a long literature existed on Condorcet domains. So Monjardet was one of the important figures because these two guys, Hemini, Nimboy and Bella wrote PhD thesis under Monjardet. Then at some point Peter Fishburne got strong interest in Condorcet domains. And Gallambos and Rayner did some important work too. And all of them, most of these work was about connected domains. So that's domains of the first type but not the second type. So those domains which are subgraphs of the permutahedron graph. Recently very important work have done Russian from Central Institute of Mathematics and Economics, Daniela from Koshyvoy and I will mention them slightly later. So our innovation is that we make all domains connected. How do we do that? So let's say that order r is between two other orders r prime and r2 prime. If r agrees with r prime and r2 prime whenever they agree. Or mathematically it can be written in this way. So an interval of between two orders. That's all linear orders that are between r1 and r2. So for example here, these all orders are everything between CBA and ABC. And BAC is between ABC and BCA. And I will give them more examples later. And that's important that we now declare two linear orders from the domain neighbors if there's nothing in between them. So like in permutahedron, two neighbors have nothing in between them. And so we get the associated graph gamma d after that. So now in the associated graph both domains are connected and there is no real reason for making a difference between them. That's one of our innovations. So condorsed domain is closed. If majority relation corresponding to any opinion of the society is also an element of this domain. So you do not go anywhere outside. And maximal condorsed domain, if it's not a proper superset of any other condorsed domain. So the two little domains in the first slide were both maximal. So condorsed domain, if you have a majority relation on some profile with odd number of waters and if it's not in the condorsed domain you can add it and it still will be a condorsed domain. So in particular this means that every condorsed domain is contained in a closed condorsed domain. And closed condorsed domain contains in the maximal condorsed domain and maximal condorsed domain is necessarily closed. So I apologize, I have to introduce another object. Eventually it will appear that all these are the same thing. But it's not clear now that they... So let's introduce median domains. So what is median domains? For every three linear order there is a median linear order in this domain. Which is between any pair of these, between R1 and R2, R1 and R3, R2 and R3. And if such a median order exists it's always unique. For example let's see here ABCD is a median of these three orders. Let's check that it's between the first two. So the first two they agree on A ranking A, C and D. They rank it in this order and this also agrees A, C, D. Now another pair they agree on B and D and ABCD also agrees with them. So you can check any pair here and you will see that indeed this is a median order. And the key lemma, very difficult, surprisingly difficult, is that betweenness, if we have a median domain, or alternatively another good case where you have the whole pyramid of hydrant, then betweenness relation on D is the same as geodesic betweenness in the associated graph. So let me show you, it's on this example. This is not a median domain and betweenness relation on D will not coincide with geodesic betweenness. Okay, so if we took A, B, A, C, B and B, C, A, then these two will be between them because this is just the reverse of that, so anything is between them. But what is geodesic betweenness? It's on the shortest path. So B, A, C is on the shortest path between these two. So this is the only thing that is geodesically between, but these are two orders that are between in the sense of domains. So in this case geodesic betweenness and betweenness do not coincide. And that is a key lemma that allows us to do whatever we can do. Now the third concept, I'm sorry, there's yet another new object. It's a median graph. It's a connected graph such that for every three distinct vertices, there is a unique vertex which is M, A, B, C. Here now I have to assume unities which is geodesically between every pair. So here M, A, B, C is between A and B because it's on the shortest path from A to B. It's between A and C because it's on the shortest path from A to C and it's between B and C because it's on the shortest path from B to C and it's unique, it's easy to check. Okay, the main theorem connects everything now together. So what it says is the main is median, the main if and only if it is closed condorsed domain. So you see condorsed domain was in terms of majority relation but the median domain was in terms of betweenness, but in fact it's appeared that it's the same thing. And for every closed condorsed domain, the associated graph is median graph. So now these two things come together. Conversely, if you have a median graph with a set of vertices V, there exists a closed condorsed domain on a set of alternatives and you need no more than vertices in V to construct such a condorsed domain and this condorsed domain will have associated graph exactly G. This is the main result but let me show you some... Now this is a contribution of Adam. Adam showed that you see in the previous result we have these restrictions that we need no more than the number of vertices for alternatives to realize this median graph. And that's the worst case scenario is when you have a star graph. So if you have a star graph with n vertices, you cannot... And I have to say also that graphs are median... Any tree is a median graph. So this is a tree but it's a median graph and you can realize it with four alternatives but you cannot realize it with three and that's what Adam proved that with a star graph you cannot realize it with less than an alternative if star graph is in vertices. Okay, so I'll show you also some beautiful pictures. It's not our invention but... So this is what you see here. It's a maximal condorsed domain for four alternatives. It's not only maximal but the largest. It has nine linear orders and it's a tiling domain. Tiling domain, that's the invention of Danilov and Karshevoy. So you have here the lowest point and the upper point in this zonogon and every snake here is a linear order in this picture. For example, you have B, D, A, C, so that's here. But you have also D, B, A, C and this is here. So these are tiling domain. That's another maximal condorsed domain. It's also tiling domain. It has one little square. It has only eight orders. This is a classical single crossing profile. So that's a corresponding graph is just a path, a line. So this is how permutahedron in the case of four alternative looks. It's already 24 vertices, this polytope. And here is what I show here is not connected in a classical sense maximal condorsed domain. So these two parts of it. But in our associated graph is a cube. So it is connected. And this is just for curiosity that's largest condorsed domain for five vertices. That's what associated graph, how its associated graph looks like. So this is distributive lattice. And Shemini and Nibwa and Danilov and Koshivoy, they showed that maximal condorsed domain is always a distributive lattice. We slightly generalized it to closed condorsed domain. But there is a condition. You have to have two completely reverse orders. Otherwise, this is not true. So this maximal condorsed domain does not have two mutually reverse orders. It's easy to check because B never goes below second position. And it's not a distributive lattice. Okay, well, interesting thing that we started to look at single crossing condition on trees. But eventually we were disappointed. We were totally now feel about trees not so good because it appears that median graph of a maximal condorsed domain is never a tree unless it's a chain. So now we feel that the more natural object is a median graph than a tree. So what are the further questions? Well, I haven't seen a complete account of maximal condorsed domains for even four alternatives. That wouldn't be too difficult, but that would be a good project for a student. And permutahedron is just a calligraph of a symmetric group relative to the set of generators, permutations 1, 2, 2, 3, and minus 1 in. And I think if we... But this is not the only set of generators for a symmetric group. So if we change the set of generators, then calligraph will change and probably disconnected domains in the first case will become connected. So it's probably connectedness or disconnectedness. It's only a matter of choosing the right set of generators for the symmetric group. Another interesting, very competitive question is that let's say mn is a maximal number of orders in a condorsed domain with n alternatives. So what's known? That was... most efforts went into this. And four values are known. So for three, we have four, maximal number. For four, we have nine, maximal number. For five, we have 20. I showed you that latest. Fishburn did enormous amount of work and I showed that for six, the maximal number is 45. So actually, Montjarde had this example and Fishburn managed to prove that it's maximal. However, we don't know m7 and with magma computing package, I believe it's possible to extend this sequence. So if you are a student and thinking about a project or for dissertation, that would be, I think, a very good set of questions. Thank you. Yeah, yeah, yeah, it grows exponentially. Oh, there are some bounds. Yes, but my talk was not about numerical values and bounds. Well, a lot is known about tiling domains. So about this tiling domains and there are some numbers for maximal values of tiling domains as they go quite far. But disconnected domains, we know nothing about cardinality of disconnected domains. And there are observations that at least by n equals 16, these tiling domains will lag behind. Other domains will be better disconnected ones. I have to be restricting almost all of the, if you're severely restricting the preference or the preference that they can be expressed by your population, it doesn't seem to have an enormous amount of probability to the original problem. I mean, it solves the problem, but it's sort of very, very restrictive. And then you realize there's almost an old opinion that people are allowed to have on all the values if you want to have a specific preference. But single peak domains are an example where you get natural restrictions because you put some ordering on the alternative straight. And so you can imagine that you end up with this sort of cutting because somehow people agree that there's some natural ordering over all the alternatives. So a good peak domain is one of the maximal domains, yes. There's some logic behind the order. Is there a natural ordering? So I guess there's an distributive lattice that comes out of one of the theorems. I'm trying to think of whether there's a natural way in which the alternatives can be ordered in order to always sustain the maximum domain. Or single peak ones. I'm assuming that no way there's some structure to the alternatives which then give you the logic behind the preferences that come out towards maximum domain. Well, if you... There are several identical notions where Danilo Kashiwoye calls this casting and Fishburne calls this never conditions. So they specify for each triple which four combinations are available. And there are four different never conditions according to Fishburne. And Fishburne found that especially the first one and the second one, if he alternates these, he can get quite large domains. All these never conditions kind of analogs of what you are saying. That single peakiness can be seen as one of these never conditions. That's a good question. Is it about the way the one was zero? Well, firstly, you mean these domains that means can there say closed under... Or maximal can there say domains? That's a good question. I haven't thought about this. Now, just one combination so you have to, instead of combining four different never conditions, you have to apply the same one all the time. We'll think about it.


The students were required to produce videos which highlight areas of cooperation and sustainable development. The project's year-long activities culminated with a prize-giving event conducted recently at the college. The video's subject matter, presentation, screenplay and narration and production values were all evaluated in relation to the sustainable development goals. The project entitled Caribe Excellence is led by Corisa, a research-based youth movement from Guadeloupe, with the Sir Arthur Lewis Community College as a partner institution. Member of the SALCC Board of Directors, Dr. Alison Gochata says the initiative is a wonderful start to what is anticipated to be a healthy partnership that augurs well for digital media students and the college as a whole. What you are taking away here today is not just the price and not just the technical know-how through the exchanges, but importantly the cultural exchanges, the new friends you've met. And in chatting to the representatives from Guadeloupe, I know there are lessons learned that we could build on as we continue this partnership to actually encourage a deeper immersion in the culture. In March of 2019, Guadeloupe joined the Organization of Eastern Caribbean States OECS as an associate member. In 2021, for the second anniversary of Guadeloupe's membership in the OECS, the Regional Council of Guadeloupe launched the call for projects in order to forward the initiatives allowing its population a better appropriation of its Caribbean environment. The project aims to strengthen the sense of belonging of the population and in particular the youth to the Caribbean basin and more particularly with the constituent territories of the OECS. On behalf of Coreca and its president, Mr. Junior Meryon, and its youth movement that I represent today, I would like to thank all the partners and of course the site for the organization of the ceremonies today, the award ceremony today, and I hope that it will be just the beginning for other cooperation of a project because we have a lot of projects that are in our mind today to do for the next months and next years. The winning video prize went to the EcoHeroes group of which Jessica James is a member. She says the group decided to work on the topic of Waste Management and conducted an interview with Director-General of the OECS, Dr. Didicas Jules. We learned a lot and enjoyed being a part of the project. For me it was a once-in-a-lifetime opportunity to interview Dr. Didicas Jules as I was already familiar with some of his work especially in the Grenada Revolution or the Amber Invasion which I learned in my secondary school history class so I'm thankful for all my teachers because I did something. Caribbean Excellence is funded by the Regional Council of Guadeloupe as part of the call I cooperate with an OECS country. From the Communications Unit of the Department of Education, Innovation and Vocational Training, I am Chris Satney reporting.


Setting it over recording Okay, and go to minty.com. You can see the code 31 35 36 very good Different avatars. Who was the winner of the last mathematics quiz? Uh, that is the most connected conducted on friday. I even I was there. I guess adin was the winner Who was the winner pronoun Shias, I remember shares shares was there. I remember I remember I remember shares was there shares was there share the I remember so guys just a notification for every one of you Uh, what will be the genre of the questions today? Okay, so the question will dominantly fall into the calculation of voltage Um, okay, that might be a voltage between two terminals that might be a voltage between two points Okay, uh, that will also include some questions from the genre of wheat stone bridge. Okay So, you know when r1 upon r2 is equals to r3 upon r4, then no current flows between the bridge Okay So 60 people are in As you guys touch 65. Should I wait for that? Uh 60 is fairly enough for me Good. So here the quiz 61 very good 62 63 very good. Very good. Very good. Hmm One and two and go Take time and one answer three Oh five very good. Very good. Relax draw calculate respond Relax draw calculate and respond Very good. Very good. Very good Actually now by this time this question should have been finished Okay, this is a tentative question of odd 40 to 50 seconds This was first witnessed in 2017 in ntsc exam 1 state deli. Okay Uh, then it was frequently another question of this type. We have already practiced with equilateral triangle Okay, and other exam site here. So 61 people have already responded not everyone has responded So we'll have to wait Okay. Oh, meanwhile I have I should have switched on my Yeah, it is there 63 very good. Very good. Very good As soon as everyone will There's someone whose mic is unmute. Please mute that. I'll have to all the over there and mute very good Thank you very much. 65 people are there in the quiz. Very good. Very good. And yes So I am explaining now 20 and 20 are in parallel 10 will be the answer. No brainer Just a drawing a good drawing was required 27 people answered at right. They are still Good bunch of people bache who are having a doubt in this Okay 65 Why don't you Read the question carefully. Carefully laksha Anybody any doubt? Thank you. I did Yeah, what have you done? No one's dropping an X very good. So let's look at the leaderboard. Okay. Good. Good. Good Ashleisha was the fastest one and the beauty of this is like all our 900 plus and that's the beautiful thing Wow very good So one and two and doom Someone already responded like boom. This question is based on your memory There will be three such questions which will come if you have Consciously paid attention to the lectures. These are repetitive numbers which have been continuously coming into existence You have simplified these this particular pair of resistance in series and parallel several times That's what is the only hint of the question. Yes, you can also formally proceed and get the answer It will be utilization of pair of linear equations and quadratic equations So now the if anyone would have even gone through the conventional method of solving it Then by now by 60 seconds, this would have been finished I have I had a lot at 100 second for this 66 people have already responded to this very good very good very good and times up Three and six ohm is the straight answer r1 plus r2 is equals to nine and r1 parallel r2 is equals to two No, are you someone responded while listening to this very good So 67 people are in total over here. Good. Good. Good. Everyone voted and yes Good majority. I forgot to announce but for ninth grade what I have made as a rule is Okay, if 60 plus people respond uh correct then burger party 80 percent people respond correct Then pizza party Okay, 90 percent 95 percent plus people respond correct then movie and pizza So for now, I had not risk as I had not announced any questions So you won't like I don't owe any price to you, but yes in general it will be followed henceforth Okay, okay. Okay. Okay. Okay. Okay Bizarre movie. Okay. Fine. Fine. Fine After lockdown, don't worry, but at least for six odd month people won't be visiting to movie halls atleast for six odd ones so here's the lead word for this okay okay okay okay okay very good very good very good very good very good very good very good sure anyone want to drop an X I don't think so wow thank you very much Tushar sir I will be there soon I am craving for it the most yeah Tushar sir is always there in any such meetings expect me and Tushar sir anytime okay we like Centrum are more than you so here we go with the third one please go for it read it carefully read it carefully read it carefully it might appear to you as a wheat stone bridge where this is not when in some questions you take 5-6 seconds and then start responding that is what is positive notification for me very good and now there should come a good wave because this was a question of not more than 50 seconds so a good wave is expected now we should cross 50 by 1 minute okay so over over over 50 cross very good 100 seconds was the time elated by me we just crossed 40 and you are 55 already responded very good very good very good expecting the correct proportions as well now again look those who have not responded don't panic look simplify solve drop in the chat what is the total current being drawn from the battery drop in the chat what is the total current being dropped from the battle drop in the chat what is the total current being drop from the battle being drawn from the battle sorry boom good good good tentatively you guys have reached 50% 2 ampere 2 ampere 2 ampere 2 ampere correct anyone want to drop an X I don't think so okay very beautiful very beautiful very beautiful there are X there are X there are X very beautiful very beautiful relax understand guys there is a 10 volt battery there is a 3 there is a 10 volt battery there is a 3 ohm resistor over here there is a 1 and a 3 here there is a 3 and 1 here okay okay okay no doubt no doubt no doubt first thing first under any circumstances R equivalent is very significant R equivalent equal to please quickly quickly quickly R equivalent only those who had dropped an X because as you have dropped in the total amount of current being drawn from the battery it is pretty obvious that you guys have a clear indication that what is R equivalent yes 3 plus 1 4 3 plus 1 4 4 and 4 are in parallel 2 3 plus 2 5 R equivalent is 5 ohm anyone having a doubt in this drop an X again again in this part R equivalent X X X N stands for no doubt I am expecting N stands for no doubt very good no and now second part the current being drawn is V by R 2 ohms no discussion on this the current will reach this junction okay now as the upward branch the downward branch are having equal Rs the current will get equally distributed 1 ampere upward 1 ampere downward right total voltage supplied to this box this box this box is 10 minus voltage absorbed by the outer 3 ohm yes or no 10 minus I into R 6 4 volts yeah so out of 4 volts as a current of 1 ampere passes through this I into R 1 volt is absorbed by this remaining is 3 volt Y or N only those who dropped an X similarly 1 ampere passing from here I into R 3 volts absorbed remaining at this point is 1 volt the difference between the 2 potentials is 2 volt that is what was asked easy I am expecting it into type sure good how do you do it fast that's the fastest method yeah I explained you this that's what I am telling this question ok should be done in odd 40 to 50 second Mahabal first questions explanation ok I will have to go back to the first question and will explain ok sure now understand first question stated what no as of now like first thing got this clear through or not everyone those who dropped in an X yeah now first question first question asked you about there are 2 registers R1 plus R2 and parallel when connected in series equates to 9 when connected in parallel equates to 2 relax who has the doubt Mahabal which question you have the doubt there are which question you have the doubt in square arrangement or series and parallel or I will take you to the question Mahabal is not responding ok it's ok Surya no problem Mahabal is not responding we will just wait for him any time we can go back to the question and do that not at all an issue for us ok here we go with the next question concentrate Mahabal don't if you are listening and did not get your answer no problem I will explain it while we are explaining the next question ok don't need to be worried about it it is still leading the game there is a good shuffle continuously happening I can read momita day also coming in Q now very good and here goes your next question solve it relax and do it 3 people have already responded 4 people have already responded but it will take time it is going to take time it will need a solution so please solve a wave coming post 10 odd second can be very well trusted they are going through the solution process calculation and responding good good good good very good and now there comes a wave always around 40 50 odd second that's beautiful good good good good good see guys a simple arrangement I have removed all those batteries and all just kept it simple at the point of a simple series and parallel arrangement in the past week we have discussed about this here so simple solution is required read the words carefully don't like misinterpret anything while translating it from English to x let's see equal distribution of correct and like why why how can it be called as equal there's a dominance of incorrect attempts guys surely there will be a good ask for x exactly exactly exactly I'll just open up the whole question why I have switched off screen share there's a reason behind it because there are other questions also in those image collections and now you won't be getting confused and also will not be able to cheat as well audible and visible is the screen visible I have reshared it is the screen visible yeah good so we are here now understand pretty simple the statement is what is the value of r ok so that the total resistance of the circuit between p and q is equal to r whatever be the resistance of this box the total resistance r is equal to the value of box plus 3 what is the value of box the value of box is 10 into 3 plus r upon 10 plus 3 plus r any doubt in this yes guys now in that case please solve this equation what will you get 13 what I'll do is I'll just send this 3 this way 13 plus r multiplied by r minus 3 is equal to 30 plus 10 r ok opening the bracket yeah exactly 69 I could see that word ok yeah good now opening the bracket what will you get quickly yes 13 r minus 39 plus r square minus 3 r is equal to 30 plus 10 r coincidentally 13 minus 3 r is 10 and 10 got cancelled 39 displaced to this side r square is equal to 69 r is equal to square root 69 ok clear there was some n no someone stated a no all those who need to respond wire relax those who want to yeah exactly r in and then good good good good good good again relax over here go to 0 and start 1 2 3 4 clear this is a 3 1 3 plus 10 is in parallel with a series the combination of 3 plus r so r1 into r2 divided by r1 plus r2 this in total is equal to nothing but r got it or not and then the equation solution and you guys have already told me that you have already been through quadratic equation solving right or not this was not even solving in a quadratic equation ok cool very good now moving to the next question let's look at the leaderboard first shuffling shuffling shuffling consistent people might be there ok there will be a shuffling I guess oh don't sleep out poora very good welcome dear Janesh I remember this boy's name he was he had been consistently responding in many of my fastest fingers first and next question relax the question today are really simple you can experience that what we have been discussing in past centimars are a bit more of elevated level of approach I have knowingly selected simple questions for today only yes before approaching toward them you will have to ok here one two next no one will respond wow wow wow wow no one I was expecting no one should respond before 5 10 seconds because yes in 10 seconds this can be solved just for a reminder which should be given as 30 seconds are getting passed in 3 2 1 go reconstruction can be suggested but yes by now this design should be it's better if you can remember this if not yes utilize the time reconstruct it and solve a good wave and now after 40 50 odd seconds notifies ok solution is being done this is being solved and then respond good 50 percent people now this no sorry odd 50 people this time did not responded within like I expect that almost 50 55 responses should have been received in 60 seconds that is 1 minute ok anyway no problem we have done these kind of question this design ok no problem no matter and now I am expecting don't be if you want to drop an X I am really expecting X relax no problem no problem no problem ok excess please good good good good good good very good very good very good I am I am expecting relax no problem now how many of you have got it correct 19 yes or no and 18 people ok and majority have got it wrong let's find out the reason ok sure what I suggested was to reconstruct that ok I will just open the thing up yeah now understand this every time the chat should be visible to me because yes understand this now and keep it with you we mark the points like I will just state P Q R S I remember this but the top and bottom wires were shorted so no problem then now this time you want to short them yes dear Pratik Shah you can re-log in ok just for you I will restate the code it is here 8 9 3 6 9 6 menti.com that's what you remember ok I am missing the chat P A no worries at P there are two tracks available one going toward Q and one going toward R one going toward Q and one going toward R ok sure anyway every resistance is equal to 5 so as of now I am not revealing that even after P comes Q at Q there are 3 tracks available one we have already traveled which is QP another track is Q to R ok and Q to S ok sure after Q comes P Q R at R there are 3 tracks 1 2 and 3 out of which 2 are already traveled R to P and R to Q R to P and R to Q R to S ok at S everything is already traveled only one path is there B happy with this all those who dropped in an X got this structure and you know which structure is this yep this is W S B Wheat stone bridge where is its practical utility in routine life where we use hmm exactly right very good very good very good if the shasar is here he might be having a smile at his face like actually literally confessing this even I wasn't aware about this thing confessing this weighing machine work on this principle ok guys and now you know as R1 R2 5 by 5 is equals to 5 by 5 there is no importance of this so we have boom and boom 10 and 10 in parallel 5 got it everyone got it everyone got it everyone got it everyone good good good proceed it's already 40 we have to rush through ok now I will not be very comprehensively commentering on everything Nana welcome to this position and here we go with the next question 63 64 people are here read it solve it apply and routine memory and logic tool you will get it like boom 30 seconds should be the time given for this question actually I was when I typed 100 I was not happy with myself I was expecting a 30 to be typed over there but then I thought that speed should not come with the cost of correctness or accuracy that's why let it be if you know R1 into R2 upon R1 plus R2 then you will have a smile on your face and the answer will be with you good good good 50 seconds 45 what people responded as we reach toward 40 let's see what's the score very good very good very good and 55 people another last 25 seconds remaining now think about it again repeat it R1 into R2 divided by R1 plus R2 that is the whole hint of this question and small small numbers and options exactly good good good and 5 4 3 2 1 25 people got it right wow the pin is here let's look at the X good Aaryan very good very good very good very good very good very good relax now statement is ok this won't even be needing a question what is the statement is the parallel combination of two registers R1 into R2 upon R1 plus R2 is 6 by 5 pretty sure yeah this is 3 into 2 upon 3 plus 2 why bungara what happened now the second statement is when one is removed the resulted outcome is 2 so when in a parallel combination just one 3 2 1 is removed the outcome is only one which is 2 ohm so which one is the removed one 3 ohm delta ok oh many issues that that is a touch problem that has been verified your touch screens are over sensitive at times ok with the cursor with the key there are yes issues but yes with the touch screen there is a different type of issue ok no problem no problem ignore ok it ok you know the answer na happy ok fine everyone let's look at the shuffling and proceed fast excuse me sir yes here I will just work on safari that's work very fine on safari no does How do you work fine on safari sir? As per the comments and feedback from our own friends, it works really well on safari. My personal experience is Chrome is really doing good. No problem. Thank you very much. And again Naina is at the top. Aiden yes, he somewhere slept down at times. Now elevating up and here it goes with the next question. Solve it quickly. Get the answer correct. Again memory based. I'll comment it as a memory based. Memory based. This pair you have already solved for several times. This is just a memory based question. Simply memory based question. Now the bling happened. Good, good, good, good. Very good, very good. Again I am repeating memory based question. A pair of three answers coming out to be as one home. This is knowingly kept over there. All the questions today are simple. I have tried my level best to bring it to the as simple level as possible. Not a complicated thing but working on the basics. Because now we are concluding the chapter. Good, good, good. Last 10 seconds are there now. 55 people responded. I don't know why this haven't responded yet. Think about it and calculate. It's hardly anything to calculate. No problem. Let's solve it out and drop your respective X. Good. At least one thing is there that the biggest number. The highest bar is of right responses. That too. It's not very high. X are intended and welcomed here. X very good, very good, very good. Better the that is 6 3 2. That is what 6 3 and 2. That's why I call it as memory basis. Simply memory based. When 6 3 and 2 are connected in parallel. What is the resultant output? When 6 3 and 2 are connected in parallel. What is the resultant output? 1. No problem. Relax. Read the question. Solve it in your notebook. 6 and 3 gives 2. 6 and 3. Parallel gives 2. 2 parallel 2 will give 1. All the 3 are equal and none of them is a fraction. That's all. That was also stated. And the ratio between 2 is 1 is 1 is to 2. Okay. Now if you are not. That's why at the beginning of the question. I stated that this is a memory based question. Several times being through the chapter. We have been through these numbers. Yeah. Very good. As you remember many of the Pythagorean triplets. These are similar kind of proportion. No problem. Okay. Let's if you want to do it comprehensively. We can do it comprehensively as well. Clear. What I'll request it as the time is getting over. Or I'll just give you a hint. You can solve out the equations at your level. Okay. So. R1 parallel R2. Parallel R3. I'm writing A, B, C. 1 is equal to R equivalent is equal to 1 upon A plus 1 upon B. Plus 1 upon C. Okay. Fine. To the power minus 1. Clear. Clear. Clear. Clear. Okay. Fine. Next. This is one. Second equation. A by B is equal to 1 is to 2. You have taken this. So. Clear. To the power minus 1. Initially I had not substituted it. But let's keep it at the basic level only. I know that because it's 1.  It will remain 1. But that will be another cutting shot. The method right or not. So that's why let it be. Let it be the formal way. Okay. Initially I was not putting it. One second time and then I kept it over there. Okay. Solving equations here. You can reach out to the answers. Okay. Clear. Next. I'll anyway put the comprehensive solutions. Okay. So don't be worried about that part. Okay. Okay. Okay. Shuffle. Again slept down. Poor up actually elevated a good level up. Janesh is still maintaining his position. Second third and here comes the next question. Concentrate over that. Now you should not make a mistake. You know the design. You know the design. You know the synthesized format of this. What will come when we'll synthesize. A known format out of this. What will come when we'll rearrange the system. Into a known named format. Giving you wider hints. Good. Good. Good. Good. I'm still happy that people are invested. Investing time reason being. You could have drawn by yourself. But yes I can sense. By the time you guys are taking that. You're trying to name that and the drawing it. Good. Good. Good. Good. Good. What has to be removed should be known. Then simplifying what all fall in series and what all goes in parallel. Will help you out to reach out to the conclusion. Okay. Good. Good. Good. Here's the time at the verge to end. 53 54 55 people. 55 55 at least 55. At least 55 please. Please please 54. Good. Thank you very much for last. Those who responded at the very last. And a good proportion. But still we have our friends struggling to. Drop down the answer X please. Good. Good. Very good. Very good. Very good. Very good. Very good. Look here. You know that this will be redesigned in the format of. Okay. And 10 will be removed. Okay. 2 4 8 4 4 by 2. Is equal to 8 by 2. 8 by 4 sorry. Okay. So that means 10 is removed. 4 12 6. R1 into R2 upon R1 plus R2. Those who dropped in X. Got it. Here in my Ganesh very good. Very good. Very good. Everyone don't be worried. We have done these kind of questions in class. Okay. Relax. Don't be worried about it. Don't be worried. Okay. Learning output is important. Yeah. Relax. But yes. Remember what we are doing in the. Discussions. Okay. The strategy. Yeah. Exactly. Exactly. Lot of questions left. Right. No odd 5 questions might be. Which question number was this. Very good. Again there will be a good shuffle. Okay. Very good. Next question. 56 people are there. 10 second. Everyone should answer. Just kidding. Relax. 10 second. 10 people answer. There's a very solid reason that in which stone bridge. Why there is no flow of current between the terminals. When R1 upon R2 is equals to R3 upon R4. Why. There is no flow of current between the terminals. Now there will be a wave coming. Guys. Which stone bridge. Why that branch that resistance which can be removed. Why there is no importance of it. That's the answer for it. Okay. Okay. Okay. Okay. 48 people by now. Another 15 seconds remaining. Good. Good. Good. Good. Good. But still there are people and similar thing. 15 9 and 9 was last time as well and 15 9 and 9 is this time as well. How many X's please. X X X X X. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. Good. And when this happens the potential between these 2 is 0 potential difference. That is where no current flows that is why you can remove the resistance connected over there. No problem no problem. That's why it's a basic definition of width stone bridge. Okay. This implies that the resistance can be removed. It's not the case that resistance can be removed. Then voltage difference gets 0. No, because the voltage difference is 0, no current will flow, there is no importance of that path, okay? Yeah, don't be worried about this, learn things, remember them kind of, okay? Again there is a shuffle, a good shuffle expected, very good, very good, very good, very good. Next question, all the remaining questions are quick, as I clicked quick, as I said very quick and then some beautiful circuit came up and these boys and girls will be cursing me, how quick? Mad man, design his own questions, take it in the classroom, brings and delivers us to the question from somewhere and these are complicated looking questions and ask us to solve, oh, oh, oh, oh. But look there, whatever type of random question we discuss in the classroom, these are analogous. I remember a similar question being asked by me in the class and Aditya responding, why, what have we done wrong to you sir? That comment I remembered and that is the reason I kept this kind of question over here. So read it, go through it, resolve a branch by branch, that's the hint of the X signs, okay? Resolve a branch by branch, you will get an answer. This is having a hint from the previous question. When B and D have a potential difference of 0, then they will create a beach stone bridge arrangement. That mean, now I'll keep mum, 5, 4, 3, 2, boom, good, good, good. First X, X, X, X, X, X, X, X, no X, good, good, good, good, relax. Now look here, reach that this is a beach stone bridge arrangement. This is sure, right? Beach stone bridge arrangement, clear? Now, this is what? 21, bye. This is what? 18, no doubt, ND, ND, ND, especially from those who dropped in an X. ND in this part, 15, 6, 21, 15, 3, 18, good, good. ND stands for no doubt for those who dropped in an X. Good, good, good, relax, fine, good. Now this part, this is 4, 4, 2, 6. So for pretty obvious reasons, 6, 3, so this box should be 7. Yes or no? Yes or no? In order this to be 7, this being 3, this box should be 4. And this is 4 only when X is equals to 8. Okay, okay, okay, okay, okay. Good, good, good, relax, no problem. So let's see the shuffle. Some consistent name at the consistent positions, minor shuffle at the base, top 3 remaining the same. Very good and here goes your next question. We should officially extend as a let's read. Quickly again, go into beach storm bridge and just like a Hulk smash it. Why like a Hulk? It's the Hulk. So like the Hulk smash it by this dialogue. There is no other hint required that watch what I did in my afternoon today, right? The correct name, a chocolate in the chat box, the correct name for the movie I'm talking about. Correct name, not the series, the movie name. Okay guys, so anyway, those who are in the physics, be in the world of physics. Those who have already jumped to Marvel's, enjoy it. Okay, shock. And here is the time and the last minute hints. Look, there is some beautiful arrangements here. They are your hints. But post one simplification, you will have to do some calculation. One go. Oh, wow. Beautiful. X please. That's a nice hint. I was expecting the beautiful timing for the hint. X are welcome. X are always welcome. No problem. But it was very high. It was very high. The proportion of people making it correct was high. Why am I drawing this? It's not even required. 5, 10, 10, 20, this is removed. 15, 30, 15, 30, this is removed. 30, 60, you know this number, no solution, 20. All those who are dropped in an X. All those who are dropped in an X. Easy, easy, easy, easy. NTSA stage 2, 2018, 1, 8. Stage 2, national level. Yeah. 10 second. 10 second. 10 seconds. These kind of questions should be just read very, very carefully. Because at times in the most simple question, thank you. No, this is a very general from many authors and question creators here. 3 and 6. And it's respective multiples and all. Okay. Let's not pull you more away from the dinner table. I know you might be hungry and all. Let's quickly rush toward the conclusion of this. And there is a shuffle. Is there a shuffle? Again, top three positions being maintained well. Next question, please. And no one responded to me for the movie name. Hey, don't please, please, please, please. I want to see everyone responded. I want to see everyone has voted or responded. I forgot the sentence even, yeah. See, understanding that at the end we will be running short of time. I've kept some these kinds of questions at the end. Good, good, good, good. I'm very good, very good 38. Again, look at it. Look at it. It's a known arrangement. You know multiplication. You know two multiplied by two is four and three multiplied by two is six. Right. And you know that what are in series, what are in parallel. And you know when things are serious, they have to be added. When you and you know when two pair of registers are in parallel, they have to be operated by R1, R2 upon R1 plus R2. Or if you don't want to operate it by R1, R2 upon R1 plus R2, you should also and you should go by one by R1 plus one by R2. Provided you don't forget to reciprocate the last line. Because generally you guys calculate one by R equivalent and consider it as R equivalent. That's the misery. Okay. Good proportion of corrects. But still X please. Very good there. And others as well. Those who are not respond. Yeah. Good. Good. Now everyone is. Relax. Relax. Relax. Okay. Understand this. Two by four equal to three by six. Y or N. Surya. Don't. This will be removed. Two and three. Five. Four and six. Ten. Five and ten are in parallel. R1 into R2 upon R1 plus R2. Okay. So clear. Clear. Clear. Clear. Clear. Shuffling. Shuffling. Shuffling. Some shuffling will happen. Okay. Good. Happen. Have you gone for the dinner? This is the last question. Officially last question. Relax. Calculate and respond. Don't get confused for your like for for taking a cautious measure. You can drop in junction dots as well. Junction dots because I really don't want you guys to make a mistake in this. Relax and answer. One single formula I have used which you should remember. Okay. Good. Good. Good. Good. The best part today what I like is we are at the last question. We exactly at eight tenths started our quiz. I will just try to manage time a bit well so that we can have a good bunch of question being solved in the exact one hour time. I really don't like we understand that you guys are staying back respecting us. Okay. And being curious. Very good. Very good. Very good. Very good. Very good. 23 people answering it right. In chat box. Last line what helped you out to reach out to the option last line P is equals to P is equal to exactly not I square R P is equals to V square by R is the outcome of this. Okay. It's the thing required. Power is inversely proportional to resistance. Hence least resistance will deliver that. Okay. So and here we are with the question simple R and 2R 1 by 2. Okay. 2R and 4R again 1 by 2. That means there is no importance of the 6R. So this is not there. Okay. How can I remove this? I can remove this like this in that case. So 3R again same thing and 6R. What is the answer? Is there still a need to calculate 2R? Clear. This will deliver the minimum resistance out of the given option by least value of R. Yes or no? 4 ohm answer. This also satisfy with a higher level of approach I will tell you. Here there is a word internal resistance is 4 ohm. There exists a this is your assignment. Okay. Read about maximum power transfer. Maximum power transfer. In electricity read about maximum power transfer theorem. Read about it. You will find something relevant with the resistance of the battery. Okay. So can you send some worksheet like this? Yes dear. I have already told few of your pals only. Okay. I will be sending. Okay. So I will be sending. I am doing it. I have already started creating that and or 10 10 sets I am creating. I am creating questions of 10 10 10 10 10 10 like not creating the question. time arranging and collecting questions in the set of 10, 10, 10, 10. The last question again, okay. R, 2R, any doubt, 1 by 2. Similarly, 2R and 4R, 1 by 2. That means this satisfies the criteria for Wheatstone bridge. Hence, you can remove this, okay. Ananya, clear that is here. I'll tell you why. Aren't, this might happen, okay, that the output, okay, okay, okay, okay, okay.  That's why I asked you to read about maximum power transfer. That's why I asked you to read about maximum power transfer, okay. So now, power is equal to V square by R, okay, or in this case E square by R. So power is inversely proportional to resistance, okay. So for least resistance, highest power. And the question also asked for maximum power, okay. Aren't, aren't done. The resistance of the load must equal to the resistance of the source as viewed from the output terminal. Okay, who is this? I am not able to read the name. Someone stated that theorem over here only. Yeah, Anish, read about it, read about it and then you will find that oh, oh, coincidentally that minimum thing here is also relevant with 2 into 2. 2R is your output, 2R is 4 and internal resistance of the battery is also 4R. Okay, read about it, read about it, read about it, clear. Take care guys. Good night. Let's go one second, one second. Let's let's let's conclude this. Let's conclude this, conclude this, conclude this, conclude this. Boom. Last shuffle. Nothing. Very good Nana. Very good. Very good. Very good. Very good. Very good. Congratulations. Take care guys. Take care. Take care. Take care. Bye bye. Bye bye. Bye bye. Good time having like good really, really this time to mark is really a good thing for within the weeks time for me really, really my signature send off dialogue even like in quarantine. I am I guess I am losing my brain cells. Can you please remind me of that? Get lost. That's pretty result for few very close to the heart. I am seriously on it. They are guys. I am seriously on live streaming a game. I'm seriously on it. There are some really seriously on it. Even I like I have discussed for some things which will be required for a line live streaming as things will just this like the lockdown will a bit losing up. Then I'll be able to buy it and I will surely do a live streaming. Mungara you stream what or tonight? Hi Gupta. How are you? So a single like a single still there? Yeah, single. So you were asking about why we have to write or not clear. The reason of that is the reason of that is the reason of that is maximum power transfer. Okay, yes if I remove that internal resistance of the battery, yeah, in that case, you just have to look into the option and respond your answer will be by yes or no hidden language. No, but if R is one home, that's why I asked you guys to go through the maximum power transfer. Go through that. Please maximum power transfer here. Okay. I had told you last time even to look into because I wanted to discuss about we have not yet discussed among us about what if in a circuit there are two batteries connected. If you remember we didn't solve the question or the theorem or the calculation of finding the equivalent output from multiple batteries, right or not? Equivalent EMF and equivalent internal resistance. We did that right or not? Okay. But yes, we have not I wanted to discuss that. What if if two different batteries are supplying power to a given network or circuit? Okay. So that we'll do. Let me match up with other batches as well. We'll do that. I wanted to do that. I really sincerely wanted to do that. Okay. Fine. So take care. Bye. Bye. Bye. Good night. Yeah, even I have parents I have to take you guys. Take care. Change man. People change when they feel the importance of the relationship and quarantine. Lockdown and quarantine. So people change their way of speaking and talking. Okay. Take care. Take care. Mungara you suggested me one that I have kept noted. I guess that might have been downloaded as well by now. What where I am struggling is, you know, like if I come on screen and stream I should not give a flop show, right? Like usually I give in sentiment. Okay. So at least game should be played well. Okay. Okay. Fine. Bye. Bye. Bye. Get lost now. Take care. Good. Good. Good. Good. Good. Our war zone war zone war zone. Yes. Exactly. I guess you only or someone told me about this. Okay. Go. Go. Go. Bye. Bye. Bye. Bye. Bye. Should I? Okay. Okay. Okay.


That's pretty much it. We're actually vlogging right now. So All right, so first thing in the morning. I'm at the gym now. I'm in my car, but I'm at the gym. I go through social media I check Kind of the activity from the day before so That's basically my morning is I go through I check everything Messages that you guys send questions And just our posts from the day before I go into the gym for a very little bit of time And then this is Tuesday. So then I head to film my podcast the Matt Beck show So we'll be doing that in a little bit. So I'm gonna get in the gym and then we're gonna head down and do that All right, so finish the workout Now how did you get ready for the show? So we're at the salon I'm gonna film the podcast It's all an extra person in there. Oh look Check it out Sup fellas Vlogging blogging. Yeah vloggers. Hello vloggers. Yeah Just sincere. That's why you asked me if I was yeah, because instead of picking the truck up late I picked it up at 8 30 this morning Wanted to kill myself. Yeah, that's how it ended all that's how we start our day. It's cold in here That's what I was reading drink. Yeah, it's true Oh and by the way Totally cut my own hair yesterday jacked it up Yeah me I did so I may need some hair assistance after this Well, and you have a cancellation I Actually called and canceled your guests so I can get a haircut I am Hey guys, welcome to episode 22 of the Matt Beck show. I actually have two Fantastic gentlemen with me today No, no, we're on 22. I know crazy We're flying through the year So we have some great questions. Thank you guys so much for submitting those. We're gonna go down the list If you want to submit a question go to Instagram or Twitter or below in the comments or call my house. It doesn't matter Ask a question using the hashtag the Matt Beck show Let's get started. Thank you guys so much for watching. We'll see you Really you had to put this song on that. It's what was all I just hit play. Yeah, right? I saw you select it Girls just want to have fun that's true. Okay, cool Yeah, yeah, we'll just set up a let's do a schedule so that we're being consistent Let's make sure that we're doing you know a post from me and a post from Denise You know every week and that that should be fine and then we'll go through and I We'll see how that works out and then we can go from there But I think that I think that'll be a good start for sure What are you doing right now? Lay out the towels and individually put a little bit of one of our shampoos So it gives a nice fragrance while it's around our guys faces Then we're gonna take them over to the shampoo bowl and get the water nice and hot and then we put them into our Nerva hot cabbie, which also sanitizes take them down Hold the towel over Roll it up Ring it out as you ring it out. It pushes the shampoo through the towel. So that way it sure is if there's even distribution Through a fragrance throughout the towel and what we do is we count out the The amount of guys that we have for the day and then we make that many towels Maybe a couple extra that we do plus a couple But it's a great service upgrade and that's you know the key because every salon does a haircut on a guy This is a little bit extra to offer and to be honest Big huge chain salons are already doing hot towels. So if your salon's not doing them You're behind the game. So make sure that you're doing We'll pick up some honeys All the honeys you guys look good My honeys, I mean all of that's kids now. She's got a girlfriend so I had a question on the on my podcast this morning and it was about um Using social media to help market yourself as a stylist um in salon And I've been talking about this for a while, but I think the biggest thing that you can do To grow your business on social media, especially a salon is just be willing to put in the time to focus on your clients and communicate with them through Social media like I think a lot of people You know, they like having a facebook. They like having an instagram. They like getting likes They like people commenting, but they they don't like taking the time to comment back and I think that's That's the biggest thing. That's the whole reason for the platform is to be social And too many people use it as just a post and get likes thing and not a actual communication tool for your guests you should be You know posting about your guests and answering their questions and encouraging them to post for you post um Post about their experiences Their challenges all that stuff you should be communicating back and forth So that's why I think snapchat is a great thing for a salon business is because you can communicate with every single guest and Use it just as your salon your professional snapchat page But allow that as a tool so that they can send you a Quick message saying hey, I'm having this challenge with my hair and then you help them out or On facebook anything like that. Just make sure that you're communicating with those with your guests Because once you start that conversation, it'll grow. It'll get bigger People will start to understand that that is what your social media is for and that'll help grow your business. So Just look at it as a social thing. That's why they call it social media. Be social with your guests Finished editing the show from this morning and Now we're just waiting for it to process. This is the not fun part of editing video. Just watching it process And Then we get to post it and see what you think. So, uh, let me know go watch matbeck show episode 22 um And let me know what you think so now real quick going to make the cover photo of the video So what I do is I go through and I select the spot where I'm Making the basically the spot where I'm making not a ridiculous face which is not very often so Find that spot screenshot it then I uh Open it up on my desktop. There's probably an easier way to do all this, but I don't know what it is. So open up the screenshot and then Take and crop that photo Because on youtube you want to make sure that you have an interesting Interesting photo at the front of your video. I guess it makes people watch it. So cropping that out now once I have that Done I open up photoshop and I bring in the photo I have my font already ready boom that's last episode change it to 22 and That is my cover photo So I just save that and I can upload that as soon as the video process and Makes it easy 77 percent almost there And I just realized I have a meeting right now. Yeah, I'm doing great. I actually um, so I've just been I filmed three haircuts yesterday and um A bunch of other video content. So I've just been I've been editing for Uh, about seven hours. So