Hey, welcome back everybody. Jeff Frick here with theCUBE. We are having a CUBE conversation in the Palo Alto studios with a many time CUBE guests. And actually, it's kind of funny. If you look back through the history of our conversations, they've slowly migrated from our studio two versions ago to one version ago. I'm really excited to welcome to them to send our new title, GM of cloud. It's a star storage. No, I'm great to see you. You too, Jeff. Thank you. Yeah, absolutely. It's funny because then we were at the little studio across the street in our, so I didn't like our new digs. I think that was the first one at the interim studio. Right. Right. Everything was still kind of in a jumble, but up and running. Yes, well, we never really passed the jumble stage. Thankfully, this place came open and moved across the street. So first off, great to see you as always. Get an update. We were just at the Western Digital event last week talking about mammor and hammer and really a lot of excitement about a new S-curve in hard drive media. Love to get your take on it. You've obviously been in the business for a long time. They were really psyched. I know there's some detractors that are, you know, still spinning rust, but it didn't seem to be the case when we were down there last week. Yeah, we're super excited. It's high capacity magnetic drives. Our customers are crazy about it. I think it's obvious that by capacity, that's a majority of our business. And the reason is that customers need affordable storage and we can provide the high capabilities, the full featured in even performance and caching and so forth around magnetic storage. We're agnostic in the sense that customers can choose SSDs and or magnetic drives, but the bigger the drives, the lower the cost per gigabyte. And our customers love that. We see extremely elasticity with regard to price. Yeah, that's interesting. One of their big themes was kind of fast data versus, they call it the big data, but really more kind of archival data or data in rest versus data in motion. And the two of them together, leveraging both the technology seems to be the right way to go. Absolutely. And customers understand that data is mixed. There are some data sets that are purely low performance. Let's call it archival or cold. Some data is really hot all the time, but most of the data is in between. It is large, it's big data, but it has parts that are hot and parts that are cold. And there's no better solution for that from performance and price perspective than a magnetic, let's call it magnetic background storage with a cash, an SSD based cash in the foreground. In the front. So let's give an update on what's coming up with Czar. Just a quick glance of the news before he came in. I see you guys are getting all kinds of award or red herring, top 100 award. Looks like Exana got to CRN Women in Channel award. So a lot of great awards and good things going on. But unfortunately, we were talking about off camera. There's a bunch of bad stuff happening. We just this never ending crash of waves of Houston then Florida, then Puerto Rico. And then unfortunately here, Northern California, I guess there's new ones. He said coming in and Santa Cruz, the fire. So it was great to see that you guys are trying to figure out what can we do to help. Yeah. Yeah, and it's, we're not insulated from the rest of the world. And so we work and we watch the news and we talk among ourselves. And we, at first we thought that we were helpless, that there's nothing we could do to help. And then the idea came, well wait a second. We provide storage services that are very easy and quick to bring up. And somebody, company that lost its storage probably needs to bring storage up quickly. And one of the challenges of course is they're probably hurting financially because the business is not running, especially if the data is gone. And also even if they're insured, there's a whole process around that. Plus everything else, fix the offices and restore electricity and so on and so forth. And we said, wait a second. Let's just do this for them now. We can help now. And then a few months later, then they can decide what their permanent solution is. So we said, hey, it's in our power to help. Let's do it. So we're offering to any business that has been affected by any of these hurricanes, storage to replace whatever they had before up to a petabyte at no cost, no commitment, nothing. Well, show us what you had before. Tell us where you need it. We'll send you the new storage at our expense. Six months later, we'll call you and say, may we have it back? And no questions asked, we'll take it back. So when did you announce this and are people starting to take advantage of it? So we've actually just announced this and we're trying to get the word out. One of our challenges is that these businesses are very, very busy with all things having to do with recovery. So they may not be able to hear what we're saying. So we're trying different ways to get the word out. So it's just trickling in now. And to be honest, we haven't cracked the formula yet on how to do this and maybe we need to talk to FEMA. I don't know. But right now we've used the commercial channels to get the word out. Well, it's very generous and super to be able to help somehow. And like you said, unfortunately, storage is probably not at the top of everybody's list when your house is burned down and your business is burned down, et cetera. But good for you guys for taking a proactive step. So let's talk about how the business is evolving. You know, we've got this big show coming up right after Thanksgiving called AWS Cloud or AWS re-event. AWS just continues to march forward at a really fast pace with Google, Cloud, and Azure not far behind. So public cloud is still booming. How are you kind of seeing market evolution? Market, is there just kind of more of the same at an increasing rate on the public cloud side? It's still where innovation happens. And there's a reason why AWS re-event gets bigger and bigger and bigger every year. It's, I'll tell you an anecdote. When we formed Zadara in 2011, we were going to put the word cloud in the name of the company. It's at, you know, and I don't know. There's a lot of cloud something in that kind of era. Exactly, so it was, you know, cloud age was one of the suggestions because our predecessors come to go store age. But we decided not to use the word cloud at all. And the reason is that we realized that if you wait long enough, cloud just becomes how IT is done. So the word will become meaningless because IT will be cloud, cloud will be IT.  So we're seeing this happening. It's becoming a default way of doing business. Definitely the OPEX way of doing business, something we've talked about multiple times. For us, it's the majority of our business. We have, so we have two businesses, a public cloud business and a non-prem business. And the public cloud business is larger. It's maybe either 60, 40, or 55, 45, split. So both nice and big businesses. But we see things changing more quickly in the public cloud. Why? Because they can't change more quickly because everything is elastic and everything is flexible and companies can innovate faster and experiment more. And route find their optimal solution more effectively. Whereas where they own their own equipment, then they're hobbled by the blessing and the curse of ownership. Right. And the other thing you mentioned off air is that that's where the real rabbits are, the real high growth companies that you guys are seeing. Because their business is growing so fast in that infrastructure and you guys basically get a piggyback along for the ride. Yes, yeah, exactly. The fun statistics dimension are those companies that are multiple of them that are spending with us 50 times more now than they were when they started per month. That's amazing. And we're not doing 50 times the amount of work, right? So they're happier because whatever they were doing they wanted to do more of and they get to do it at the push of a button, we're happy because we're seeing more revenue. Also we're adding more value. And at the same time, it's neither one of us is resting in our laurels. We have to re-earn the business every day because any day that customer can say, I'm terminating, I found a better way to do it. So we have to make sure to keep them happy every day. And then they're happy because they have sort of insurance or future proofing. They're not stuck with us. Right, right. If they need to tack left, they can tack life. It's interesting. We did the Zora subscribe show and kind of the attitude that you have to take with a customer when they're paying you every month versus paying you once and then collecting a maintenance fee is you have this ongoing relationship and you have to continue to keep delivering value because they're getting that bill every single month. So you got to make sure they're not only happy with the service but you're over-delivering and innovating and continuing to provide more for that dollar. So it really creates a tighter relationship with your customer. You got it. And the really strategic customers understand that and they take advantage of it in a positive way and they put a premium on the agility. And an example is one of these 50X customers got quite big as you can guess and we decided, hey, we should probably get this customer in a longer-term contract because it would be kind of painful if they call us tomorrow morning and cancel. So we went to them and said thank you for your business as a reward for your business and to introduce some stability, we'd like to offer you a discount, a significant discount for a 12 month commitment. And they said no, we'd rather pay list and have the freedom to change. And we thought, that's amazing. This is a whole new world where what you pay for is flexibility. Right, right. And then on the private cloud side, what's interesting is we've got a concept here, with the true private cloud, is they want to have that same flexibility and that same agility but just not necessarily have the data at Amazon or at Microsoft or at Google but still have all those capabilities and flexibilities to execute in the cloud-based matters. And you said it's just the way business is done. It's not even really a place. Right, so we have a car manufacturer, top very small number car manufacturer and they are worried about industrial espionage. So their design data cannot be in anywhere that's network connected. So it can't live in the cloud by definition. So we provide them storage as a service on their premises in an air gap network, that has no connection to the internet whatsoever. And then we have a mechanism with them where we do billing offline. So they expose to us their usage in a way that we consider trusted and then we build them accordingly. But we cannot access the system remotely nor can anyone else. So that's one example. Another interesting thing is that because we offer our own hardware at Amazon and Google and in Microsoft Azure, we can actually provide the paradox of how do I use, how do I run an application at AWS let's say without exposing my data to AWS?  You want to use them because they have capabilities that they have. But per your corporate risk guidelines, AWS is a competitor, I mean Amazon, the parent company is a competitor. You can't actually do that. But we solve that problem because when you use us at AWS, you're not storing the data at AWS, you're storing on us. We're connected to AWS via private high-speed fiber with very, very low latency. So your experience is a local experience. We look like local storage, but from a data governance standpoint, it's not at AWS. And in fact, not only it's not at AWS, it's on your own dedicated drives, be they the big magnetic drives we talked about or SSDs. So if you need to have these drives for any reason, you can have them. We will sell you the physical drives that contain your data. You want to crush them with a steamroller? Go ahead. So is that like the direct connect concept? Or are you in the physical, are you at their physical building? I was used to laugh. What does direct need mean? How close is it across the street? It's really close. Across the building, across the IOA and the data center, across a plane of steel in a box, kind of closest close on the same board, but down a little ways. So they won't exactly tell you, because they're secretive about where their actual servers live, but we can test the latency and draw conclusions. It ranges from the next building over to the same building. You don't know. You're just told, terminate your fiber here and we will connect it the rest of the way. And you don't know where the rest of the way is. But yeah, another way of putting it is, it goes from one to two milliseconds and that's it. So that's basically inside the data center or the next building. Very, very close. So we'll keep picking on AWS because the show's coming out. Here's gonna be 45,000 plus people, it's bananas. One of the things when you watch Andy speak, Andy Jassy, it's just this continuous innovation. It's funny, I saw him speak in San Francisco earlier this year and S3 and EC2 was like the itty bitty little corner of this giant slide that had a ton of lives, this constant pace of innovation. As you look for it and it's a different kind of attack than looking for these big, giant gains. They just are constantly moving. What are some of the things you're looking for as we turn the calendar on ending 2017, looking forward to 2018 at Siddharah as it just continued to make incremental change. Is there any big things out there that you're looking at or big goals you're trying to achieve or just keep doing what you're doing and doing better? So the first big picture strategy is at AWS, we provide premium storage. If you think of AWS as engineering effort on storage or any of these many, many, many other services is they have an audience of one million customers plus to serve. They need to develop things to serve that audience. It's hard to justify the development for the elite sub-sub-subsection, but that's our target market. So if the pyramid, base of the pyramid is a million customers, we're focusing at the top 1,000 customers. And our business model is all around those 1,000 customers. So we can afford to invest in pleasing those customers at AWS while AWS invests in the million customers and at the end of the day everybody's happy because we complete the list of critical features for AWS, which means AWS can attract customers that they otherwise would not be able to attract or to be more precise, attract those applications from those elite customers that the customer didn't think they could move into AWS. Just like the story you just told in terms of the separation of the data. Precisely, that company is a Fortune 10 company. So they are very, very demanding and we have other stories like that. So from a strategy perspective is keep adding value to AWS customers above AWS' own very aggressive roadmap. They're developing, they're releasing new features and over time those features overlap with what we do, but that's okay. If that's a slope up, ours is a slope up too, that's higher than the AWS slope. So that's overall strategy. In furtherance of that, we do plan some, at least one big announcement for 2018. It'll be our third generation architecture. I won't spoil any of it, but it is designed from the ground up. It's quite exciting. It has some of the latest technologies that are flying around as buzzwords and I can tell you they're way more than buzzwords. They work, it's just really cool stuff. Our engineers are having a lot of fun with it and yeah, I'll leave it at that. Okay, well I can tell by your face that you're excited about it. They've probably been working really, really hard. All right, well, no, I'm always great too to catch up. Welcome to our new studio. And I guess we'll see you in Vegas if not before. I will be there, I can't wait. Absolutely, all right. He's Tom Shander, I'm Jeff Frick. You're watching theCUBE from our Palo Alto Studios. Thanks for watching.


My name is Mo Doliwal. My background is actually in software development, but a number of years ago I sort of stepped into the cultural sector as a volunteer, sitting on the board of the Bangorau Festival, the Wally celebration, the Alliance for Arts, a number of organizations, and that's sort of the place where for the last seven years I sort of cut my teeth both in the arts sector and learning about cultural diversity. Provincial Maseko Awards is a program created originally sponsored by the provincial government and it's essentially an awards program, but it's a way of recognizing the organizations, the individuals, the people in the community that are enhancing and furthering their own diversity initiatives and adding to the diversity and the multiculturalism of the province. Through the Provincial Maseko Awards program, what we're trying to do is really reinforce those good behaviors and create those habits in our community that will make sure that whether it's an individual working in the community or whether it's an organization that's hiring practices, that they continue to further the cause of multiculturalism to continue to reflect the community that they operate in and bring British Canadians together. Well, the benefits aside from being recognized for your efforts is there's also an attached cash prize, so as a business owner if you're applying for the Maseko Awards and you happen to win the Maseko Awards for your organization, essentially we provide not only recognition and a lot of promotion, but also a $5,000 cash prize and then that business can use that money to fund another program or further the diversity initiatives within their organization.


Everybody force the lane here. We got 20 23 flaws collegiate football one box number 13 left side serial number Let's randomize and rip. Good luck everybody Go six times here five and one first one two three four five and six Ken W down to Ken W and six times on the numbers one two three four five and six 17 down to seven Yeah, Jordan. I saw a tick talk about that it is kind of messed up. So virtual gift cards the way to go It sounds like yeah, yeah, the verge that do not buy a gift card from a store Good to know like the sealed gift cards what they're doing is like opening that cardboard cutting the gift card in half Taking the card number and leaving the like scan part So you're going to the store buying what you think is a gift card and you only have half the gift card Ken W 17 Anthony and 20 Billy F 12 Stephen B 14 Sean O 22 Troy S 23 Adam P 19 Michael S 6 Brett K 13 Tim S 18 Brian T 16 Eric W 15 D W 2 Brett W 8 Rick H 24 Wayne P 25 Kevin W 4 Jonathan L 9 Sean 0 5 Andrew B 1 James M 21 Michael S 3 Kevin W 10 Billy F 11 and Ken W 7 Yeah, I was going to say that's just going to be an extra step for people to get gift cards then I thought I saw makes them not refundable It should just sold the gift card. Nice. Yeah 90 go guys dual case a backable coming up pretty damn soon. Let's get it going here. Come on single digits. Yo Watch the hero out the poor here. Watch this. Watch this Missed the peak perfectly planned. I miss the peak guys. Sure. That works Joshua You'll pass out of Tim Sam Laporta Laporta 9 of 10 9 spots What's up the names here 9 is for Jonathan L? Triple patch Baker Mayfield Kyler Murray and Caleb Williams 6 of 10 I did try by that shield. You look at the look at that Caleb is a sooner. Look at that That's crazy. Yo Baker Kyler and Caleb 6 of 10 6 spot is Michael S For as good of quarterbass as they've had it's wild that they've never actually won anything meaningful. Yeah Yeah, I got a RPA horizontal case on butte a 10 of 20 10 spot is Kevin W Team logo signatures Daxon Hill 17 of 20 17 spot Ken W I thought they should have had that one. You're the head Baker in the playoff for the Washington, Georgia. Yeah They should they should have had that game very good. They should have had that game Nice Daxon Hill there It's a cool looking one. That is an older card here. Rashad Bateman RPA 9 of 20 Where's Sam when we need him? Jonathan L with the nine spot that is a 2021 Flawless Collegiate patch auto Horizontal RPA Zach Charbonnet 3 of 20 nice three color patch For the three spot Michael S Stetson Bennett 5 of 15 horizontal RPA 5 spot Sean Oh All right, Charles Woodson 7 of 20 17 of 25 rather 17 of 25 diamond gem Charles Woodson 17 spot again Ken W 2 it's for 17 A high number It's a diamond guarantee Number to 5 of 5 rookie emerald sam la porta 5 again Sean Oh Sweet la porta gem at 3 of 5 Anthony Richardson Rookie patch auto horizontal Michael S with a big card three color patch Richardson 3 of 5 That does it for the break everybody big congrats Michael on the back there Moving on to another Flawless Collegiate


Now, we talk about the importance of meiosis. What is the importance of meiosis? The most important feature of meiosis is the genetic variation by recombination. As we know that the natural environments in which the organisms are living, they are always changing. The temperatures change, the sometimes earthquake comes and the whole environment is changed. There are different types of environmental factors which always they are modifying, the availability of foods, the availability of shelters and everything changes and the organisms have to modify according to these environments. These recombinations by the crossing over in the prophase one of the meiosis provides the basis of new recombinations and this provision of new recombination makes new characteristics. These characteristics if are suitable for the organism and makes it more fit for the environment, the organisms survival is improved. So, usually the organisms have a better survival if they have new good characteristic, but it could be otherwise if the characteristic which appears is not good, then the survival will be reduced and as we know that the Darwin's theory says that the fittest will survive in an environment. The second benefit is this that because of meiosis half number of chromosomes go to one gamete and then the gametes have to combine and during as we know from the anaphase because we covered anaphase. In anaphase this is not necessary that whole set coming from the grandparent will go to just gamete, just one gamete. There will be a mixture because in anaphase the chromosomes are arranged in homologous pairs and in each pair there is this is not necessary that the paternal chromosome from father will be on one side and the chromosome from mother is on the other side, but this may change. So, there is a fifty-fifty chance that the gamete will have the paternal chromosomes or the maternal chromosomes. So, in each gamete there is a mixing or combination of few paternal and few maternal chromosomes. This provides another degree of recombination. This is the most important feature of meiosis. This is the importance of meiosis, the genetic variation which makes usually the organisms more fit to survive in the changing environments. Just have a look in the diagram which shows a homologous pairs and then shows a recombination, a chiasmata formation at two places and this chiasmata formation at two places as you can see if we look at their genes in the initial chromosomes there is a combination of capital Y, small Y for example, in a plant this is for yellow and green. These are the genes for yellow and green seeds. After recombination we can see that the first one will become yellow, the second one may become a green, the other one may become due to a recombination and in between color. So, a genetic variation arises due to these recombinations in meiosis. Now what happen if an error occur in meiosis? Errors in meiosis could have serious consequences or disadvantages. Usually errors in meiosis comes from non-disjunction. To understand the non-disjunction we have to look at a diagram. As we know that meiosis have two phases meiosis one and the meiosis two which results in formation of gametes. As you can see in the first diagram on the left in the n-phase two when the chromosomes have to move from the center towards poles. If the homologous chromosomes are not separated in n-phase one then what will be the result that the whole homologous pair will go towards one cell and the other cell will not have any chromosome on its place. So, that will be empty for that chromosomal pair that whole homologous pair. Then these two cells will divide by meiosis one they will result in unequal formation of gametes. As you can see in the first one it shows an n plus one that is one extra chromosome is here. The second also have an n plus one but the other one where no part of homolog went the chromosome is number is n minus one that is one chromosome less than the haploid number and the fourth one is also n minus one that is one chromosome less than the normal haploid number n. This is called non-disjunction that is in n-phase the homologous set which should naturally or normally separate are not separated but they moved towards one pole only and the other pole did not receive any chromosome. This non-distinction could occur in the meiosis two as well sometimes what happened that meiosis one completes correctly and both of the cells which are the result of meiosis two they have the correct number of chromosomes and then they start with the meiosis two but at n-phase two when they have to separate as the diagram on the right shows when they have to go to the poles in one of the cells division is normal and the chromosome number is m but in the other cells which is divided into two one chromosome with both of its sister chromatids move towards one pole and on the other pole there is no chromosome because one sister chromatids as normally as you can see in the last right diagram should go towards one pole and the other sister chromatids should go towards the other pole but what happened that both sister chromatids keep attached to each other did not separate and they move towards one pole only and the other pole remains blank the result is again we call it a non-distinction no separation and the result is one gamete which is n plus one that is haploid number plus one extra chromosome and the other one is n minus one that is haploid number with one chromosome less now as you can observe in these two diagrams and if you compare both of these non-distinctions the first one non-distinction in meiosis one and the second one the non-distinction in meiosis two if we compare those we can see that the non-distinction in meiosis one is more dangerous because the result is all the four gametes have abnormal number of chromosomes but in the case of non-distinction in meiosis two we have two normal gametes and two abnormal gametes so it means that if non-distinction occur in the meiosis one then the result will be all abnormal gametes more dangerous but in case of non-distinction at meiosis two we will have two normal gametes and two abnormal gametes that is 50 percent correct and 50 percent incorrect so this is non-distinction and what will be the result if these unequally distributed chromosomes in the gametes will combine with a normal ag sperm and will be fertilized to make a zygote the individual which is formed will not be normal this results in different types of diseases at birth you can see here an individual the picture with a down syndrome which is a mental disorder the child have inabilities intelligence inabilities and have many other problems and the reason is that if you can see in the yellow circle the chromosome number 21 have rather than two normal parts of a homolog it have three homologs just non-distinction in one chromosome only out of out of 23 pairs in just one pair there is a non-distinction and the fusion of the gametes I mean one gamete from normal parent the normal gamete and one gamete from a parent where a non-distinction occurred which have an extra chromosome the result is a very serious disorder down syndrome all the chromosomes you can see the one two three four five six seven eight are normal the last is also normal just at one chromosome and there is we call that three chromosomes are present in the set rather than two homologs there are three homologs which are present it means that a slight disorder a slight problem a slight non-distinction just even in one chromosome may result in a very very serious disorder this is and there are a lot many other disorders which may occur due to non-distinction at different types of chromosomes so errors in the meiosis may result in serious inborn disorders and as you can see here it's a very serious mental disorder in person is in unable to run the normal life in normal circumstances and they need special attention now the last topic for today twins twins we know if we look in in our lives normally many pairs of the twins one sometimes two pair maybe three or more there are two types of twins one is called fraternal twins the other are called identical twins we sweetens are in our normal life many times we see that they are just like each other in in their height in their face in their color in their features everything is just alike and they are of same gender both are male or both are female both boys and both girls but sometimes we see the twins which are actually very different from each other and who don't like don't look like twins they have different heights they have different features they have different religions different character other characteristics actually according to the divisions there are two types of twins one is called fraternal twins fraternal twins are those twins which look to us different from each other just as the siblings are different from each other which which are born at different times what happened that they are actually produced by different eggs sometimes the more than one eggs are produced by the ovary and both eggs are separately fertilized the result is two genetically different individuals they are as different as those individuals are which born in different times but the identical twins they are produced by the division in the same egg what happened that an egg is produced with the haploid number but it somehow divides by mitosis into two and when the egg is fertilized after its fertilization it divides into two which means that zygote is divided into two we also call them mono zygotic twins because they are product of same zygote they have exactly same genetic features they have exactly same type of chromosomes so they look just just as each other they must be they must have same gender both our boys or both our girls they are identical totally thoroughly in their genetic recombinations and in their genetic characteristics but there is there is another thing which may makes them different as we know that characteristics of an individual particularly its behavior does not only depend upon the genes genes play their role but the interaction of environment with the genes or we can say the gene environment interactions make certain characteristics particularly the behavioral characteristics and the intelligence by various studies in different parts of the world shown that if identical and mono zygotic twins they are grown up in different situations and conditions they develop different types of intellectual skills they develop different types of behaviors according to the environment in which they are grown up they are brought up it means that genes alone are not responsible for all the characteristics of an individual but the environment plays its role and the environment and genes both of these interact with each other to produce a full individual a complete individual with all its characteristics life is a production of genes in interaction with the environment so this was all about meiosis its significance its errors the results of its errors the twins interaction of the genes and environment I hope you understand


Welcome back to my channel guys. In today's video, I'm going to show you guys my hat collection I got a request to show you guys what hats I have since I showed you guys my lack of color hat I don't have a lot of hats, but I have like a nice little handful So I am not going to show you the lack of color because I have a whole video on that and I will link that Somewhere around here for you guys to take a look at but I'm just gonna get started a lot of these hats are Kind of old, but I feel like I keep seeing them being Reissued or Revamped or whatever and coming back So I'm gonna start with the first hat and this hat is kind of old. It's by yes tat Y E S T A D T and It has like a really hard brim almost like the lack of color hat now I like this hat because you can wear it with like Graphic tees and stuff like that Again guys, I will not wear this with a bang or my bangs will be out of my face the only issue with this hat is that it is This piece here This little detailing it's kind of hard and If you have a larger head or even if you are wearing a unit you might have trouble So with something like this you can wear it Going backwards, you know a lot of the girls wear the hat towards the back of the head with maybe like a Shacket that's ladies are wearing now. Maybe like a plaid shacket or whatever So this is the first hat. I do like the detailing on this hat My only issue is this piece here. That's Extremely hard well, I can get it on but it kind of hurts my head because It's so fitted. It doesn't stretch. So something like this you wouldn't necessarily need a hat filler And like I said, this is kind of old but I can find something out here like this for you guys It is a hundred percent wool. I try my best to get a hundred percent wool If not, the hat's not really gonna last me and I'll show you so that's hat number one This one here. Actually, you guys could actually see the little detailing on it like the lack of color It's just a hard of brim So that's hat number one Hat number two It's one of the hats where it's not a hundred percent wool and I know this because I know I didn't pay a lot for this one this oh I didn't cut the tag out guys I'm sure it's like a 50 50 blend or something like that But this is more of a cheaper version of the other hats that I'm gonna show you But I bought it because I did like the color the color was very cute and it's just something that You know, you would just wear Just out, you know, maybe going shopping It's just it's I don't like hats like this that do not have the The extra piece at the rim the brim of the hat Depending on the quality of the hat. So this is more of a cheaper one. This probably was like $20 maybe maybe $20 guys But I like the color. I had some boots that were this color. So I got this hat. So That's hat number two I like the color like I said, I would recommend getting a hat that has more of a structured brim It is a shorter one, too. This detail is actually cute But as you guys can see it's very floppy but it's not as wide as some of the other hats that I'm gonna show you and If you are gonna go for a cheaper brand Then I would say Make sure that your brim is wider like this one. I Think I overpaid for this one. However This is a hundred percent wool The hat is a hundred percent wool.  So this one doesn't have that Hard piece at the brim of the hat. However It's bigger as you can see It's bigger than the other last hat that I just showed So something like this you can wear with pretty I'm sorry guys I'm looking into the mirror to make sure that it's not crooked But something like this I would wear with Probably a button-up shirt maybe a long white button-up shirt dress and some boots Keep it really simple. I'm tall. So it's very hard for me to really find longer button-up shirts When I do I do buy multiple shirts guys That is the key to shopping as a tall lady and I'm gonna say this a million times if you find shoes or jackets or jeans Buy more than one because it's very hard for us to like really find things that fit us properly and You know when they're sold out, they probably won't get any more. So this is hat number three and This hat is from sacks. I think I did a full review on this hat Like I said, I think I overpaid for it in my opinion That's just my opinion. So that's hat number three hat number four is An older hat this hat is by aqua it is a hundred percent wool and it was made in Italy This is one of my favorite hats. It doesn't have that indentation like the other hat does Because this is more of a fedora style The shape and this is not I'm not even sure what the shape of this hat is but this hat is so cute Because it's very feminine like you could wear this with some brown boots You could again you could wear this with a white button up in some jeans if you wanted to keep it really simple for the day This hat has a larger brim or so, but it doesn't have that extra piece But I like this one because the top of it is more rounded out if you guys can see and I do like the brown detailing on it Um This can go with pretty much anything. So it's like a tan Creamish color not super light like my lack of color hat, but it's still in the same family But this is something that I would just wear Just out and about guys out and about and I love it Let me know what you guys think about this one and if you I mean when you are buying hats Just pay attention to this top piece Something like this. Let's see It's probably a one-size-fit all Yeah, I would definitely put this in the cleaners and see if they can dry clean this just so you don't have any Issues with your hat because it like I said it is wool But I don't think you would need a hat filler if you did you do have the space Inside to put the hat filler in if you have a smaller head now if you have a larger head You might be out of luck But I think you should be okay I think that's number four Number five And this is not all of my hats. This is just some of them that I Think you guys would like the other ones are like summer hats and stuff This is actually the same brand as the first black one with the tight Rim what a tight piece here detailing same brand It's just it's in gray and again, this is a hundred percent wool. I will recommend you guys getting that So it could last you you don't want to have to keep buying hats over and over and over because you're buying a cheaper hat, but if you want to buy a color Maybe you can because it made the color may go in and out of style But when it comes to like grays and blacks and Grays blacks and tan colors and browns maybe stick with what? Stick with a hundred percent wool So looking at this hat I'm just now looking at it and it has it's a little cricket, but I think that's how the hat is made because of Where the boat is at and you're probably supposed to wear it on the side so Again, you can see this little detailing right here. I don't know. This is where this is. Oh, no, maybe that was just me guys. I Didn't tuck it in properly So like something like this again, you can wear like the first one This is not as tight as that first one It doesn't have that I don't even know what material that is around. It's like some sort of wire But this one is a little bit better Gray is very classy and can go with a lot. You can wear it all black. You can wear blushing gray You can wear gray and white and maybe a tad of yellow Most of some colors that I would wear it with and if you have some beautiful beautiful snake skin boots or pumps with Gray not the tan color snake skin, but more of the black and white and gray This will go perfect with it. So this is hat number five and My final hat See guys my hair keeps getting messed up. My final hat would be this baby This baby this baby. So I showed you guys three black hats This hat is from BCBG and I bought this some time ago And let's see what it has here It does have the place for the hat filler. It gives you some detail. It is one size fit all And They are calling it just a felt floppy Now where is the oh? actually Look at here guys. I Had this hat for such a long time. It actually comes with a hat filler. So this is great I can probably use the same hat filler. I don't know if you guys can see like velcroed in Inside, which is great The lack of color did not come with it. They definitely charge you like $5 for it, but They could be nice and add it in for you. So this hat it doesn't even show I'm trying to make sure it's a hundred percent wool and it's not so Probably because it's from I don't know it's BCBG. Um, but here's this one This one is a little bit more Boom because it has some leather detailing at the top It does have that difference. So this is more of a fedora style more so than the tan color that had the rounded out top But here's the last hat guys Just make sure that your hat.  Definitely. Maybe a trench coat or something with this. I'm like a nice tailor trench coat. Um, I Know Mackage has a lot of Nice trench coats and wool coats, but they to me they run kind of small so another suggestion is going to suit supply and getting a Wool coat custom made to fit your body Especially if you are tall If not, you can go there and get your measurements because I don't think all states have a woman's section If they don't go and get measured and then go from there and get your coat made I definitely think it's worth it. That's on my little wish list that I'm gonna do I don't think it's expensive given the fact that I am tall So that's what I would do. But here's the last hat guys and that's it This is my little hat collection. Like I said, I'll do a summer one when summer hits because I do have summer hats But since we're in fall and going into winter, I think these were appropriate for this video guys If you like videos like this guys, please comment below Any other videos you would like to see And if you stay to the end of this video, please hit that subscribe button And comment Coco we see you and I will see you guys in the next one. Bye


it literally outlines, it reverse engineers how to create a healthy happy relationship with one another. See most of us don't have role models, most of us don't have a blueprint of how to integrate lives together. And this book, amongst the many others I recommend, and again the book is listed below the seven principles for making a marriage work, gives you a blueprint of how to establish a relationship together. This book right here, Nonviolent Communication by Marshall Rosenberg and I Hear You by Michael Sorensen, because these two books give you a better understanding of how to communicate with one another. See many of you think of communication like this blah blah blah blah or more so like this blah blah blah blah. Remember that from Charlie Brown?


Welcome to the lecture on lexical analysis. In this lecture, we will discuss lexical analysis in detail. What is lexical analysis? Why should lexical analysis be separated from syntax analysis? What are tokens, patterns and lexemes? What are the difficulties in lexical analysis? Recognition of tokens. So, for this we require fundamentals of finite state automata and transition diagrams and then for specification of tokens, we require regular expressions and regular definitions and we will study all this and then finally, we will take a look at a very effective tool called lex for lexical analyzer generation. To do a bit of recap, this is the block diagram of a compiler. So, the lexical analyzer is the first component in a compiler. It takes a character stream as input, outputs a token stream which goes into a syntax analyzer. So, this is where the lexical analysis actually is performed. So, let us go to the details. So, what exactly is lexical analysis? The input to a lexical analyzer is a high level language program. So, it may be it is written in C, it is written in C plus plus or java or any other language, but the common feature of all these is that they are sequences of characters. There is no other distinction between these programs. They are all sequences of characters and the output obtained from a lexical analyzer is a sequence of tokens. So, the tokens go into the parser for syntax analysis. The lexical analyzer does a lot of cleaning on the input. For example, it strips off the blanks, tabs, new line characters and comments from the source program because these are not very important for parsing. Once the token stream is formed, these are not at all important. So, these are all removed by the lexical analyzer and then the tokens are formed. The lexical analyzer keeps track of numbers, the line numbers and associates error messages with the various lines of source code. The error messages might have actually, you know, arisen because of syntax analysis or semantic analysis or even lexical analysis, but these errors are all kept track of by the lexical analyzer and then, you know, associated with various numbers, source line numbers of the program. The lexical analyzer also performs preprocessor functions. For example, hash defined and hash include in C. So, hash defined defines a macro and hash include includes a file.  So, the lexical analyzer actually performs this expansion wherever that name appears, it expands that name with the sequence of characters mentioned in the hash defined macro and then, submits that expanded sequence to the rest of the lexical analyzer. Hash includes simply says, now, you know, take this particular file, it is also a part of the program. So, perform compilation on it. So, hash includes simply means, start reading from a different file and then, do lexical analysis and parsing etcetera on the rest of the file, which is mentioned in the hash include. So, separation of lexical analysis from syntax analysis, I already mentioned this briefly in the last lecture just to do a recap. The first reason is the software engineering reason, it simplifies design. A compiler is a very, very large piece of software, millions of lines of code. So, making it modular is essential and making the lexical analyzer a separate module helps in reducing the complexity of building a compiler. As I already mentioned, the I O issues are limited to lexical analysis alone, the errors and so on, reading from different files because of hash include etcetera etcetera. And it also makes lexical analysis, you know, if it is separate, it is actually more compact and faster. You know, the parser becomes more compact, you know, fast apart from the lexical analyzer itself being very fast. Why? The reason is lexical analysis is based on finite state automata. These are much easier to implement in the form of tables rather than implement, you know, the functions of the lexical analyzer in the push down automata which uses a stack. This will become clear as we go on in the course and study parsing as well. So, the comments blanks, you know, need not be handled by the parser. So, why not remove them in the lexical analyzer itself? So, that makes the work of parser a little less. A parser is obviously more complicated and therefore, keeping track of, you know, number of lines of code, names, comments etcetera, you know, it is absolutely unnecessary for the parser. So, the lexical analyzer is a better place to take care of these and this makes both the lexical analyzer and the parser more efficient. Now, let me define tokens, patterns and lexemes and then go on to the operation of lexical analyzer itself. So, let us take a running example. It is a programming language statement similar to C. Float absolute 0 Kelvin equal to minus 273 followed by a semicolon. Here, as we know, float is a reservoir, abs 0 Kelvin is a name, it is a variable and it could also be seen as a constant. It depends on the type of usage that we want for it and minus 273 is an integer constant. Now, on this particular running example, we are going to show what are tokens, what are patterns and what are lexemes. A string of characters which logically belong together is a token. For example, the word float and the word abs 0 Kelvin are separated by a blank and they are obviously two different strings of characters. So, we can very safely say float is a token, then abs 0 Kelvin is another token, the equal to assignment is one token, the minus sign is another token, the number 273 is one more and then the semicolon is the last token in this particular sentence. So, once the tokens are identified, you know these are actually passed on to the syntax analyzer. So, the tokens are treated as what are known as terminal symbols of the grammar specifying the source language. This will become clear as we go on. So, that makes the life of parser a little easier. It need not worry about the characters making up the token float, it needs to worry only about some kind of a number called float that is it. So, internally tokens are going to be represented in the form of integers and that makes a token stream very efficient. Then, what is a pattern? The set of strings for which the same token is produced is called as a pattern. So, we are going to define what are known as regular expressions to define these patterns later, but for the present let us understand what exactly are patterns. So, in this case the pattern is set to match each string in the set of strings that it supposed to match. So, for example, in for the running example the word float is a pattern on its own, because no other string actually matches this particular pattern, but for the identifier or the name we have a general pattern which says later. So, we have a pattern here L is of a letter and then D is digit and then we have underscore. The plus actually is a form of the notation it the way to read and then star is for iteration. So, let me explain what this pattern is. It says letter followed by either letter or digit or underscore any number of times 0 inclusive. So, we can produce for example, the way abs underscore 0 underscore Kelvin is produced. We have a letter then followed by two more letters. So, in this case letter or digit or underscore any number of times is exercise to produce two more letters and then it is exercise to produce one underscore. Then four letters another underscore and then five more letters. So, this is the sequence which is actually exercise to produce that particular name. So, that is a pattern for the identifiers or names. Then equal to star these equal to and minus sorry equal to and minus match or patterns which match themselves and nothing else and finally, for the integer number constant D plus D is a digit. So, any number of digits together, but plus says at least once you know the digit is used at least once. So, the number cannot have 0 number of digits it should have at least one digit.  So, these are the patterns. So, the central theme of specifying lexical analyzers would be to come up with a formalism to specify these patterns which cover the entire programming language the set of programming language constructs. So, we are going to define regular expressions which can do this job very admirably. Finally, what is lexeme? A lexeme is a sequence of characters matched by a pattern to form the corresponding token. So, in other words this is the pattern and that is actually the name identifier. So, the characters which form this particular identifier actually are the are form of this lexeme. So, the string will float the string abs underscore 0 underscore Kelvin the string equal to the string minus and the string 273 are the sequence of characters and they are called the lexeme corresponding to the tokens. So, we have talked about tokens very briefly. So, let us discuss it a little more to understand how tokens are actually used for specifying various parts of a programming language keywords operators identifiers. So, we will always say identifiers instead of names then various types of constants integer constants floating point constants then literal strings these are string constants punctuation symbols such as parentheses brackets comma semicolons colons etcetera and many more. So, these are the various types of tokens that are possible in a programming language and we need to specify patterns for each one of these tokens. A unique integer representing the token is passed by the lexical analyzer to the parser. So, as I told you each token is given a name by the designer. So, representing it is very efficient then tokens you know if the number corresponding to token does not say everything about the token you also need extra attributes extra values for these tokens. So, let us see what values are required to specify a token completely for names or identifiers the lexeme of the token or the string corresponding to the token or a pointer to into the symbol table where the lexeme is stored by the lexical analyzer that is in summary we require the string corresponding to the name. So, that is also to be accessed in you know while doing parsing or semantic analysis also code generation etcetera etcetera. So, that is one of the attributes that we want for the identifier and then for integer numbers we want the value of the number similarly for floating point numbers float num we want the value of the floating point number in the appropriate you know representation and so on. For strings we need the string itself and the exact set of attributes are dependent on the compiler designer. So, it is possible for example, here it is possible that the token contains the string corresponding to the name itself in the case of identifier some other designer may say you know let me store it in the table and provide a pointer to the symbol table. So, that is the description of what kind of tokens arise in programming languages and now let us also discuss the difficulties in lexical analysis. For example, certain languages do not have any reserved words. So, in fact while do if else etcetera they are reserved in C, but they are not reserved words in the programming language P L 1 and in FORTRAN some keywords are context dependent. So, let us take an example take this do 10 i equal to 10.86. Do 10 i is an identifier and do is not a keyword even though this is supposed to you know it looks like a do loop in FORTRAN because this says do 10 i equal to 10.86 do 10 i will now be taken as an identifier a name and do is not separated as a keyword, but if the statement were to be do 10 i equal to 10 comma 86 then definitely this is a do loop and do is a keyword. In fact the tokens for this particular statement would be do a reserved word 10 a label name then i another identifier equal to and then the integer value 10 comma and another integer value 86. So, these are going to be the various tokens for this particular statement whereas, the previous statements we have just one identifier do 10 i then equal to and then floating point constants 10.86. So, the sequence of tokens for a statement would be very different depending on the fact whether it is a you know do statement or a different type of assignment statement etcetera. Handling such features requires what is known as a look ahead. So, here until you know when we see do 10 i it is not possible to determine that it is a variable or the do statement. In fact we need to go and pass this 10 find whether it is a comma or a dot if it is a comma then it is a do statement, but if it is a dot then it is an assignment statement and only after reaching this comma or dot can we really determine in the token sequence even for the previous stream of strings you know the previous string. So, whether it would be one variable followed by equal to or it would have a reserved word followed by a label name and then variable so and then equal to. So, the token streams are going to be very different and the token stream can be determined only after looking dot or a comma which actually succeeds the string of characters 1 0 in this case. Then blanks are not significant for turn they can appear in the middle of identifiers, but in C C plus plus Pascal etcetera it is not. So, blanks actually separate various tokens lexical analyzer cannot catch any significant errors except for very simple ones like illegal symbols etcetera etcetera and the rest of the errors are caught by the parser. So, if an error occurs there is very little that the lexical analyzer can do apart from skipping characters in the input until a well formed token is found it just keeps skipping characters skip one character try to find a token skip another character try to find a token etcetera until it succeeds and really finds a meaningful token. Now, specification and recognition of tokens. So, regular definitions a mechanism based on regular expressions are very popular for specification of tokens. So, we will look at the details of regular definitions and regular expressions in the following lectures. The regular definitions have been implemented in a tool called lex. So, if we write regular expressions then you know automatically the tool lex produces a lexical analyzer. So, we will discuss regular expressions and then token specification using lex regular definitions and so on. We also use transition diagrams which are nothing but variants of finite state automata. So, they are used to implement regular definitions and to recognize tokens. Transition diagrams are usually used to model the lexical analyzer before translating them to programs by hand. By the way it is possible to write lexical analyzers by hand as well in the olden days that is exactly what was really done even today for a very small languages for efficiency sake it is compiler designers sometimes write lexical analyzers and parsers by hand. So, it is not as if it is very artificial to think of such a situation. So, when we design regular you know lexical analyzers to be implemented by hand we use transition diagrams to model them and then translate these transition diagrams by hand to programs. Whereas, lex automatically generates optimized finite state automata from regular definitions it does not require transition diagrams as a method of specification. So, we will first study finite state automata and their generation from regular expressions in order to understand transition diagrams and the working of lex itself. So, now for so far we have looked at tokens we know what tokens are and but we still do not know how to specify tokens and once we learn how to specify tokens we will see how to translate them to programs. In our study of you know token recognizers or lexical analyzers we require to define languages finite state automata and regular expressions. So, let us go through some of the definitions and understand them. A symbol and a symbol is really an abstract entity and we do not really define it. It is assumed to be known to everybody it is like a set for example, sets are not defined you know mathematically they are just abstract and everybody is supposed to understand them. So, examples of symbols are letters digits etcetera what is a string a finite sequence of juxtaposed symbols that is symbols place one after another is a sequence of symbols. So, such a sequence of symbols is called a string. So, if we consider the letters a b and c a b c b c a b a they are all strings over the symbols. Now, well it is very easy to see that you can form any number of symbols any number of strings given these three symbols a b and c infinite in fact. If you write mod w then you know mod w is the it stands for the length of the string w and is actually the number of symbols in this string epsilon is the empty string and is of length 0 these become very important for our form all definitions later on. And what is an alphabet it is a finite set of these symbols in our case most of the time you know we will be using characters as symbols and set of characters would be our alphabet as appropriate to various programming languages and what is a language. So, this is not a natural language such as English and nor is it a programming language such as C or Pascal this is a mathematical entity called a language and it is defined as a set of strings of symbols from some alphabet. So, you take symbols like a b c that is a set of three symbols a b c will become an alphabet and then you know you can form any number of strings over it and if you take some of those strings put them in a set and that set becomes a language. It is not necessary that languages be either finite or infinite all the time there are finite languages and there are infinite languages. So, the null set and the set containing the null string epsilon are both defined as languages that is by definition. The set of palindromes over 0 1 is a infinite language because there are infinite number of palindromes and you can form using two symbols 0 and 1. The set of strings 0 1 1 0 1 1 1 only three strings over the alphabet 0 comma 1 is a finite language why is it called a finite language there are only three strings which is a finite number and the set contains only these three and therefore, it is a finite language. So, if we say sigma is an alphabet then sigma star is the set of all possible strings over sigma. So, if you take a single symbol 0 then starting with epsilon 0 0 0 3 0s 4 0s 5 0s in general 0 to the power n with n greater than or equal to 0 this set is an infinite set and that would be the set of all strings over this sigma which is nothing but a single symbol alphabet containing 0. But similarly you could define sigma as 0 comma 1 then all possible strings formed using 0 and 1 obviously this is an infinite language. So, this is called as sigma star.  So, that is the formal definition of a language. So, you could have finite subsets of sigma star and obviously you can have infinite subsets of the subsets which are infinite sets. So, those are also possible. So, there are infinite languages and finite languages. So, now there is a tricky you know description the set of languages over sigma star is uncountably infinite why in general if you take a set right and then you define the set of all subsets of that set that is known as a power set. So, that would have 2 to the power n elements if n is a the number of elements in the base set that is the finite set will have a power set of cardinality 2 to the power n. But once you have you know sigma star as an infinite set the number of elements in sigma star is infinite. The number of subsets of sigma star is also infinite but it becomes what is known as uncountable. So, I cannot really spend too much time talking about what is uncountability because that is a part of discrete mathematics. In general set of numbers like 1 2 3 infinite set of this kind is countably infinite whereas, the set of subsets of an infinite you know infinite sets such as sigma star is uncountably infinite. So, in some sense uncountably infinite is in quotes bigger than countably infinite in the mathematical sense. Each language must have now let us look at this carefully each language must have a finite representation otherwise we cannot talk about it. So, a finite representation obviously can be encoded by a finite string. So, any finite representation you know can be encoded in a small string how long that string is that is up to the representation to decide. Thus if you choose a particular sigma and then each string of that sigma star can be thought of as representing some language over the alphabet. So, because you can say each such of each string encodes you know a finite representation and that becomes you know some language representing over this alphabet sigma. So, it so happens sigma star itself is countably infinite the what I said here is set of languages over sigma star is uncountably infinite, but if you take sigma star it is countably infinite and the set of languages over sigma star is uncountably infinite that is a bigger thing than this sigma star hence there are more languages than language representations. The moral of the story is no matter what type of finite representation you come up with for languages. So, that it can be they can be processed by machines that is compilers, interpreters etcetera etcetera you know this particular representation will have it is limitation. In other words you cannot come up with representations for every language that is possible there are more languages than language representations. So, but that is not going to be a big disadvantage for us because we are there are more than ample languages available in the representations that we choose and they are more than sufficient for our practical purpose today. So, we are not really worried by the statement that there are more languages than language representations. So, the available representations are sufficient to take care of all the languages that we know of today. Future of course, we have no idea what would happen. Now, there are what are known as type 3 or regular languages. So, now we will go into classification of these languages. These regular languages can be represented in a finite way using what are known as regular expressions. So, the languages are infinite, but the representations are finite that is the basic idea of any representation. Then there are type 2 or context 3 languages again these are infinite, but then the grammars context 3 grammars which we are going to study later form a representation of these languages again grammars are finite objects. So, they are finite representations. Then we have context sensitive grammars which represent context sensitive languages again context sensitive grammars are finite representations of infinite languages and type 0 grammars are finite representations of type 0 languages. So, here is the hierarchy regular languages are weaker than context 3 languages, context 3 languages are weaker than context sensitive languages which are in turn weaker than type 0 languages. So, this hierarchy of languages is known as the Chomsky hierarchy based on the you know to respect the inventor who you know proposed this hierarchy known Chomsky. So, let us look at some examples of the languages. So, sigma let us say is a 3 symbol set a comma b comma c and that is our alphabet. The first language L 1 the set of all you know a's and b's a to the power m b to the power n that is a number of a's followed by a number of b's, but m and n are not related it is just that m and n are greater than or equal to 0. So, you would have epsilon then you would have a b then you would have a b square a cube b 3 etcetera. I just give examples of strings from this language, but it is an infinite set with no relationship between m and n that is very important. L 2 is a similar language, but it says a n b n n greater than or equal to 0. So, the number of a's is equal to the number of b's and the b's follow a's here the number of a's and b's are not related, but the b's follow a's. So, the first language can be represented using regular expressions. The second language cannot be represented using regular expressions, but you need context free grammars. Let us look at the third language a to the power n b to the power n c to the power n n greater than or equal to 0. So, the strings are a number of a's followed by equal number of b's followed by equal number of c's. So, the difference between these two is the c part this had only a's and b's being equal, but we here add c's also which are in equal in number two number a's and b's. So, once you do that this language fails to be regular it fails to be context free, but is what is known as a context sensitive language. So, we require context free grammars to represent L 3 context sensitive grammars to represent L 3, context free grammars to represent L 2 and regular expressions to represent L 1. Showing a language which is type 0 is outside the scope of this course, but you know very very intricate you need many more mathematical arguments before we can show that. So, I am going to omit it. So, now what exactly are automata? Automata are machines. So, what do these machines really do? These machines accept languages and those languages you know correspond to the ones that we have already defined. For example, finite state automata accept regular languages and they can be specified using regular expressions. Push down automata accept context free languages and they can be specified using context free grammars. Linear bounded automata accept context sensitive languages and they can be specified using context sensitive grammars. Turing machines accept type 0 languages and they can be specified using type 0 grammars. So, these are the four types of automata which are extremely important in the study of languages and automata theory. For our purpose we restrict ourselves to the finite or state automata and push down automata. Finite state automata are used for regular for lexical analysis and push down automata are used for parsing. There are many applications of automata. For example, finite state automata have been used extensively in switching circuit design. Of course, I already mentioned it is used in lexical analyzer. Then the Unix tools grep and arc AWK they perform string processing and are based on finite state machines. Object oriented design for example, UML it uses what are known as state charge. They are nothing but extensions of finite state automata. Modeling control applications for example, an elevator operation can be easily specified using finite state automata. Parasets of all types use push down automata and of course, compilers you know there are tree automata and so on which are extensions of the finite state automata which are used in compilers for code generation and other purposes. Let us begin our discussion of the finite state automaton. A finite state automaton is said to be an acceptor or recognizer of regular languages. I have already mentioned this. It is a machine really and it can be programmed. Let us look at the formal definition of a finite state automaton. It is defined as a five tuple quintuple. First component is Q which is a set of finite set of states. Then there is a sigma which is the input alphabet for this particular machine. Then we have delta which is the transition function. It requires a little more explanation and I am going to do that after we run through this definition. Then one of the states in Q is designated as the start state and it is represented as Q 0 and F is a subset of Q and whatever is in F is a final state. Now, let us get back to delta. As I said the finite state automaton is a machine. So, delta tells you how the machine progresses from one state to another on consuming a particular symbol from the input. So, delta is the transition function. It is a mapping between Q cross sigma and Q from Q cross sigma to Q. So, in other words we write it as delta of Q comma A equal to Q 1 something like that. So, it means when the machine is in state Q and the next input symbol is A the machine changes the state and goes to the state for which is defined as delta Q comma A. So, that is the state it enters. So, in one move from some state Q the finite state machine reads an input symbol, changes the state based on delta and gets ready to read the next input symbol. As I show you an example it will be very clear. A finite state automaton accepts its input string. If starting from the start state Q naught it consumes the entire input string and reaches a final state. So, both these conditions are very important. It is not enough if it consumes the entire input string, but is in a non final state and it is not enough if it reaches a final state and there is some more input remaining. Both must happen and it must start from the start state Q 0 it cannot start from some other state. So, in such a case the automaton is said to have accepted the input. If the last state reached is not a final state then the input string is rejected. In other words it reads the entire input, but then enters a non final state then the input is not a part of the language or rather it is not accepted by the finite state automaton. So, let us take a simple example. So, you start from the start you know here Q naught Q 1 Q 2 and Q 3 these are the set of states of the automaton. Q naught which has an incoming arrow hanging incoming arrow is the initial state and then there are two states Q naught and Q 2 which are special which have double circles. So, these are the final states. So, Q naught Q 2 is the set F then the delta function is shown by these arcs and the labels. So, when the state delta of Q naught comma a is Q 1. So, in other words from the state Q naught on input a the machine goes to the state Q 1. Similarly, from the state Q 1 on input c it goes to the state Q 2 etcetera. So, from Q naught it goes to a goes to Q 1 on a and on input b comma c it goes to the state Q 3. So, let us look at the formal description of this in the next slide. So, as I said it has four states Q naught Q 1 Q 2 Q 3 sigma is a comma b comma c Q naught is the start state and F is Q naught comma Q 2. So, you can observe that Q naught and Q 2 are the final states. The transition function is identified by the table below. So, let us look at it from Q naught we already know on a it goes to Q 1 on b it goes to Q 3 and on c it goes to Q 3 etcetera etcetera etcetera. Now, let us look at the machine again and see if some string is accepted or rejected. Let us take the string a b c. So, we start from the start state Q 0 the first symbol is a. So, we go to state Q 1 the second symbol is b. So, from Q 1 on b the machine actually stays in the state Q 1 consumes the b and on the final symbol c it goes to state Q 2. So, the input is exhausted and it has reached a final state. So, the string a b c is definitely accepted by the automaton. So, you can now see that a single a followed by any number of a's and b's followed by one c this set of strings is accepted by the machine. Whereas, any string which begins with a b or c it enters a state Q 3 from which it is not possible to get out or the state remains there. So, if you consider the string b a c. So, on b it goes to Q 3 and on a it stays in Q 3 and again on b c it stays in Q 3. So, on b a c starting from the input state you know the start state Q 0 it ends in Q 3 after exhausting the input which is not a final state. Therefore, the string b a c is rejected by the automaton. So, the accepted language for this particular set is the set of all string beginning with an a and ending with a c of course, epsilon is also accepted simply because this particular state the start state without consuming anything will also is a final state. So, epsilon the input string with of 0 length is also accepted another example. So, again we have Q 0 Q 1 Q 2 Q 3 as four states that is a set Q and the state Q 0 is our start state as usual, but it is not mandatory to make Q 0 as a start state all the time even though that is the notation which is used in a very text book. It could be Q 3 as well but the designer can use a different notation if he or she desires the set f is just Q 0. So, only Q 0 is a final state and all others are non final states. So, in other words if the input you know takes the machine from Q 0 to some other state after exhausting the input then the input is not accepted, but if it brings it back to the initial state then the input is accepted. Delta is here. So, what is the language? So, delta is always shown in the form of a table or in the form of a picture, picture is easier to understand. So, we have used pictures in our case the language accepted is the set of all strings of 0's and 1's in which the number of 0's and the number of 1's are even numbers. So, that you can check you know on a single 0 I go here on even number of 1's you know I keep circulating between these 2 states right. So, for example, 0 and a 0 right and then let us say it go through a single 0 then on a single 1 I go here but then I have to consume another 0 to get to Q 1 and finally, I must consume another 1 to get back to Q 0. So, if I consume only odd number of 0's and or odd number of 1's I will never get back to Q 0 I will remain in one of the other states Q 2, Q 1, Q 2 or Q 3 and therefore, those strings are not in the set of accepted strings. So, we saw an example of finite state automata now the language accepted by a finite state automaton is the set of all strings accepted by it that is starting from the start state the you know the string x which is the input string must actually take you to the final state it must belong to the final state. So, this notation is an extension of the notation where the second component was a single symbol but that is a very straight forward extension. So, we can say delta of Q naught comma the string must take you to a final state. So, this is the language you know all the strings of this kind which take you to the final state from the start state or in the language accepted by the finite state automaton and this is what is known as a regular language or a regular set. So, this is how we define a regular language one of the ways in which we define the regular language later we will also define regular expressions and regular grammars which are also you know specifications of regular languages but that is not the task right now. Of course, it can be shown that for every regular expression a finite state automaton can be constructed and for every finite state automaton a regular expression can also be constructed. So, we will look at this briefly a little later. Now, what we have seen so far are finite state automata but there is something very special about it they are what are known as deterministic finite state automata. So, why are they called deterministic? The deterministic automata do not permit more than one transition from any state on a particular symbol whereas, for non deterministic finite state automata they allow 0, 1 or more transitions from a state on a given input symbol. So, to show you a simple example on 0 from the state q 0 I can either remain in the state q 0 or go to the state q 1. Similarly, on a 1 I can either remain in the state q 0 or go to the state q 1. So, in you know this is an example where the non determinism shows the machine can decide to stay in q 0 on a 0 or it can decide to stay by you know jump to q 3 on a 0. So, this is exactly what is non determinism. So, it allows 0, 1 or more transitions from a state on a given input symbol. So, the finite state of NFA the other one is called as a DFA deterministic finite state automata and this is known as an NFA but the transition function delta is different here it is the same phi tuple, but the transition function is very different. So, for example, delta of q comma a it used to be a single set in the case of a DFA, but here it is the set of all states p such that there is a transition labeled a from the state q to the state p. So, it is a set here and one of the elements of the set could be chosen by the automaton at any point in time. So, for example, in this case you know so from the state q 0 on a 0 the delta function says it is a set consisting of q naught comma q 3 and for this on a 1 it is a set consisting of q naught comma q 1. So, either q naught or q 3 can be chosen by the machine. So, delta in the case of a DFA was represented as q cross sigma to q that is for a given combination of q and symbol a single state was possible, but here a set of states this is the power set notation a set of states which is a subset of the set of states is possible. A string accepted by is accepted by an NFA if there exists a sequence of transitions corresponding to the string that leads from the start state to some final state. So, it is very similar to the previous one you know in the case of DFA we said it should go from start state to final state on the input here it can go from a start state to any one of the final states it is not necessary that it goes to the same final state every time it can go to any one of the final states. So, and then still we say the string is accepted. So, every NFA can be converted to an equivalent deterministic finite state automata that accepts the same language as the NFA. So, this is a very powerful result which says the non-determinism does not really add anything to finite state automata. So, we are going to look at that result in some detail later on. So, let us look at this example here there is non-determinism and the language is the set of symbols x such that x contains two consecutive zeros or two consecutive ones. So, let me demonstrate how this works. So, it is you know from q 0 it can consume any number of zeros and ones, but finally it should go to q 3 and then to q 4 that means it would have at least two consecutive zeros here followed by any number of zeros and once again in q 4. If it has taken this path it can have any number of zeros and ones in the beginning, but then it must consume at least two ones enter q 2 and then it can have any number of zeros and ones in this state as well. So, two consecutive zeros are two consecutive ones that would be the rule to make a string acceptable to this particular automaton. So, we will stop here and continue with non-deterministic automata in the next lecture. Thank you.


YouTube team keep it clean What's going on is engraving here with another video on this rainy Tuesday evening And just a quick side note for the people that went here yesterday when I was going through the car problems I mean, I'm still the car that battery light is still on But I did talk to my mechanic and he said that it's probably the alternator So I'm getting ready to go drop it to him right now as we speak. But anyway, I Just wanted to revisit something that we talked about a few days ago With Andrew Sendejo and his hit that he put on the Ravens wire receiver. Mr. Mike Wallace I wanted to actually readdress that again because Watching the game live Is one thing but then being able to actually go back and look at the play again is another And I just wanted to talk about what I saw and how I felt the hit was and what I felt about it And whatnot anyway before we get into that. Let me introduce myself. What's up, Anthony? Me I'm engraving vids. This is my YouTube channel engraving vids, and I'm a Ravens fan struggling Ravens fan of Devoted Ravens fan, but a frustrated Ravens fan. But anyway, um, they appreciate that Anthony. Thank you. Thank you And even though I'm a Ravens fan on here, we talk about Ravens all the time But we also just talk about NFL period So if you're Ravens fan, what's up level maker it was up Charles If you're Ravens fan, if you're Vikings fan, if you were fan of football period doesn't matter make sure you subscribe Leave a like on the video if you haven't already turn your notifications on that if you haven't already And let's get into this and don't ever be afraid to say what's up, man And if you want to follow on Twitter Instagram Snapchat all that good stuff everything is engraving vids everything is engraving vids But I appreciate y'all I really do sincerely I do Now The hit that Andrew Sendeo put on Mike Wallace Mike Wallace was getting wrapped up by the cornerback and then Sendeo came and bow Mike Wallace Hellman came off head hit the turn bounced on the turf and That was the last player the game Mike Wallace even fun with the ball to drop it whatever Was it a dirty hit my personal opinion? When I look looking at it live is one thing looking at it in a replay and watching it over again Why the game is not on is another but do I think it was a dirty hit? Nope. I don't I Do not Think that it was a dirty hit. I do not think it was a dirty hit at all at all Was it it wasn't an unfortunate hit.    No, was it an intentional leading with the head? I really do not think so I don't believe so reason being I Don't I don't think it was dirty at all because What it looked like with and this is my opinion and he could let me know if you agree Let me know if you did if you disagree the one is fine But what I feel what what I saw what happened Was that the corner back Mike Wallace caught the ball and the corner back?  It did not look intentional to me It didn't look intentional to me it didn't look dirty to me It didn't look like he was trying to take Mike Wallace out the game It didn't look like he was playing dirty at all. I really it to me.  I know he appealed He did appeal to suspension, but it still got upheld. They just said that a Believe like 15 maybe 30 minutes ago, but so he's still gonna be suspended for the game They got coming up against. I believe it's the Browns in London or England or whatever So, I don't I don't I don't think I don't think it was I don't think it was a dirty hit I really don't I think he was just he was trying to make a big play He was trying to make a big hit but it looked to me like he was leading with his shoulder and With since Mike Wallace was still in the process of getting taken down or getting tackled or whatever It just seemed like he was just a bunch of coincidence Like it didn't I don't think if Mike Wallace would have still if Mike Wallace would have been still I don't think it would have been a helmet to help me But I think since Mike Wallace he was still moving Because he was trying to fight for yours and the cornerback was still trying to take him down Since he was still in the process of moving then he just having to connect with sendeo's head and It looked a lot worse than it than it actually was to me To me I just I just don't think I just don't think it was it was a dirty hit. I don't think it was a bad hit I mean it was a bad hit, but I don't think it was dirty wasn't illegal wasn't nasty. I don't think so mark I really don't think so Who cares about the hit. Let's just win Thursday No, man Me to say if I was Mike Wallace, I'd thank him. I wouldn't want to be on the field I don't know man anyone see the flacco elite thing on bleach report. No, I didn't see it yet I had to check my to it in a little bit. I had to check it in a little bit But anyway, yeah, man, I just wanted to come on here and let y'all know how I felt about it just Just to put it out there. Um, so Doesn't matter what I think though because the NFL says that it was dirty and that hit is It cost him a game. So he won't be playing in England So I don't know if that was one of his lifelong dreams while he was a kid growing up to play the NFL In london one day, but cendales not going to get to do that this coming sunday But anyway, appreciate y'all man. Thank you. Again, let me know if you think the hit was dirty and why or if you think it Wasn't dirty and why so I appreciate y'all coming through again Make sure you subscribe to the youtube channel turn your notifications on and leave a like on the video if you haven't


What's up? This is fun. Holy smokes. I've been up a two mile warm up, feeling real good. By the way, I don't know if I slept so good before race out last night. It was absolutely epic. Okay, remember, pack the blue towel to stretch out on here in the parking lot. Just getting organized, getting my big number on. And I'm going to roll out, stretch out. And then I got about 30 minutes until the start. So as far as timing goes, that's what we're looking at. All right, we need this. Don't need that. Stretched out, shoes on, ready to rock and roll. Got my water bottle to take to the starting line. That's my tip of the day. Always take a water bottle that you can, you know, just set on the side. You don't care if you lose it. So that's what I'm going to do with this. And we'll just see you at the finish line. Sound good? Cirque series? Snowbird. That's rock and roll. Come on. Super psych, super psych. You're coming along for the journey today. We're bringing the GoPro. Come on. This is fun. Holy smokes. Oh gee. All right, there we go. Just hanging out with true love. She's excited. Of course, you know true love. She's excited. But I haven't told you all something. Something's about to go down. First of all, I'm going to go to the awards here in a minute. But what I have not told you, I'll tell you in a few minutes, it means, what I am going to tell you, it means I got to go do a ridiculously solid cool down right now, roll out, stretch out, all that good stuff. So all right, see you at the awards. I got another athlete in a, what is the right dissension maneuver? I told you I like chocolate. I need to find a chocolate sponsor. That's what I need. Yeah. Ladies and gentlemen, the top three ladies to cross the line. This is good. If you're from Colorado, you know. This dude from the ghetto. All right, here we go. Funny. Funny is amazing. Chip time, one hour, 20 minutes. Thanks, man. I appreciate it. It was fun. Ladies and gentlemen, fire up those cameras. Put those hands together one more time. Respect these cats. Good work. I'll be there. I'll see you in Jackson. Okay. All right. All right. So Julian right now has a very special, and you know what? This is that moment where the music is going to turn down. Do I keep this? Special dude. All right. Julian's got a moment to speak about the next one. Let's see who suits us. Let's see Jacob. And I believe you have pretty much every single one. All right, everyone. Wow.  Thank you for all your support on Strava and Instagram and everywhere YouTube.  So I've made it to my sleeping location for the night in near Park City, Utah. And eating my banana, recovering as quick as I possibly can. I'll explain in a minute.  Push. Peaks. It's amazing. So peaks is a keyword. And so you're probably wondering why did I pay so much attention to recovery after the race and to washing my singlet after the race in the creek. So here's the deal. I am, when you're watching this, I am racing another trail race. That's right. A buddy of mine back in Denver, a running buddy, he made it known to me that there's, and I knew about this race earlier in 2019, but I frankly had kind of forgotten about it. So it's the XTERRA US Trail Championships. Something like that. And it's spelled X-T-E-R-R-A. That's probably how you could find some results. And I would not recommend this. Doing this on the fly. But how's the saying go? Strike the iron while the fire's hot. So I have been doing ultra running and crazy mountain adventures. We're talking like 30 to 50 mile mountain adventures in like a 36 hour window. So as far as my body, I know I can handle it. So I would not recommend this to folks who maybe are just starting to dabble in trail running. But I can't resist. I'm going to go for it. And I'll keep you all updated once again. So that is the update that I was talking about earlier today, back at Snowbird. And so anyway, that is the situation. When you're watching this, I'll get you, so I'll get you updates on Twitter, Strava, Instagram as quick as I can today. When you're watching this today, September 8th, I believe it is. Again, thank you for the support. And everybody that I met in person at Snowbird, High Five, it was awesome. Met a lot of you, a lot of locals in Salt Lake City. So that was sweet. Question of the day, how was your race this weekend? And if you didn't race, what is your next race on the calendar? Maybe it's the fall, maybe it's next weekend coming up. So that's the question of the day. I hope it went well. And yes, that is it for today. Again, shout out to everyone out there for the support. I appreciate it. Hope you enjoyed the edit and the epicness at Snowbird. All right. How are we going to close out the vlog with a couple of old vlogs? So we're going to go with on the right-hand side, the last Cirque race that I was at, but I did not race. I filmed it at a basin. And on the left, we're going to go with the last time I was at Snowbird, the Speed Goat 50K. I've shown it a couple times recently, but it was a tough race, tough, tough race. All right. Thanks for being here. Thanks for watching. See you tomorrow.