Today we are going to start the second chapter, it is called first order partial differential equations. In this chapter we will study first order partial differential equations and Cauchy problem associated to that and what are the possibilities in terms of existence, uniqueness and maybe non-existence as well we will discuss. Now in today's lecture what we are going to discuss is how the first order PDEs appear, how they arise and the Cauchy problem, initial value problem and initial boundary value problems, what are they we will discuss briefly. So the outline for today's lecture is the first point is how the first order PDEs appear, we will see two situations, one of them is going to be a physical situation and the other one is within mathematics, mathematical situation. And then we define these terms Cauchy problem, initial value problem, initial boundary value problem for first order PDEs, we look at 3 examples which suggest us what happens or what can happen to a Cauchy problem in terms of existence of solutions, uniqueness and then we look at a simple first order PDE for which we consider IBVP that is initial boundary value problem and we study what are the possibilities there. Now how the first order PDEs appear, so first order PDEs arise in many situations, we are going to just see two instances, the first one being as a mathematical model for a physical phenomena, in fact what we are going to see is not really a physical phenomena it just models the traffic on a highway and then we see as equation satisfied by some mathematical objects. So this is the physical model which we are going to look at today is a mathematical model for traffic flow. So in this model we are going to have two main ingredients, we will briefly introduce them. So one of the most fundamental physical principles is what are called conservation laws or balanced laws and one encounters them already in course of mechanics where we would have seen conservation of mass, energy and angle momentum. So we are going to derive a PDE model in a similar situation, we call it simpler because no a priori knowledge of anything is needed including physics. As I told you we are not going to do really a physical model, it is going to actually model of the traffic flow which can be easily understood. So let us consider an express highway without any intermediate entry or exit points. It has one entry point, one exit point, you cannot join the expressway in between or you can leave, both possibilities are not there, leaving and joining is not possible. So the traffic what we mean is let us say vehicles, let us say cars just to refer very easily, assume that vehicles are moving in a straight line. As we know vehicles do not move straight lines, they will be overtaking one another but what this means is that this gives us a way to identify the highway as an interval in R and it actually physically means that overtaking is not allowed, maybe the expressway is very narrow so you cannot overtake. Now let rho denote car density at a point x in R, yes, rho is not infinite but then we are going to finally specialize to certain intervals. So at the time instant t, what does this mean, car density means what? We can get the number of cars by integrating with respect to x. So let a be less than b, then the number of cars in the interval a b in terms of the highway it may be a stretch between a point a and a point b, at time t is given by the integral of rho over the interval a b. Now we need to know how it changes, so the instantaneous rate of change at time t is given by the derivative of this number d by dt of the integral a to b rho x t dx. But who is really responsible for this change, it is a cars which are entering at the point a and leaving from the point b. Therefore the same number is given by the influx of cars at a minus outflux of cars at b which is qat minus qbt. Both are same numbers because we made this assumption of no entry and no exit. Thus we have this balance law, so both these quantities are balanced therefore d by dt of integral a to b rho x t is equal to qat minus qbt that is the balance. So the balance law is now d by dt a to b rho x t dx equal to qat minus qbt. Now we are going to modify the right hand side, the right hand side we write it as an integral. So if you use this fundamental theorem of calculus will give you qat minus qbt. So interchanging the order of differentiation and integration in the first term d by dt is outside the integral we can take it inside. Yeah of course we know that this is not true all the time it is not allowed one needs justifications but this where I say no bargaining ends at the very first instance. So do not ask that questions right now, they can be asked later. So now once the d by dt go inside the integral the balance law becomes a to b rho by dou t equal to minus integral a to b dou q by dou x. Now let us take the RHS to the left hand side and then the balance law becomes integral a to b of this quantity dou rho by dou t plus dou q by dou x equal to 0. Now this is true for every a and b such that a less than b. In other words you have integral of certain quantity is 0 over every interval a b it means that integrand has to be 0. This is an exercise in analysis we would have encountered many such situations for example if you take a continuous function integral integrate on any interval a b and if the result is 0 then the continuous function has to be 0. And there are generalizations of this which may be let us say locally integrable function if you integrate on any set and the integral is 0 then the function must be 0. So these are two typical instances where we can conclude this. Now what remains is the equation has a row that is what is the traffic about we want to study about this but there is a unknown quantity q the flux it is not known therefore we need to model that. Therefore it is reasonable to think that q depends on x time t and the density of course itself that is rho. So q can be thought of as a function of x t and rho this kind of proposition of what kind of a function it is of the variables x t and rho is what is called a constitutive law. Of course there will be as many models as the number of constitutive laws. So constitutive law models how q depends on x t rho consider a simplest constitutive law which is given by q of x t rho since x t is not involved in this formula I have not written x t. So q of rho equal to c rho where c is a positive number. This means the flux is proportional to the number of cars. So substituting this in the balance law what we get is dou rho by dou t plus c times dou rho by dou x equal to 0. This equation is called a linear transport equation. This is a linear equation is clear because the unknown quantity rho itself does not appear what appears is their first order derivative dou rho by dou t and dou rho by dou x it appears with the power 1. So this is a first order linear equation c is a constant. Therefore it is a linear equation why is it called transport equation something must be transported from somewhere to somewhere it must be from some time t equal to something to future times. So in deriving this model recall that there were two main ingredients first one was balance law and second one is a constitutive law or constitutive relation. Balance laws are very general constitutive relations model the specificness of the situation in this case of the highway. So in our model we use the constitutive relation as q rho equal to c rho in general q may be more general function of x t and rho in that case the balance law becomes this dou rho by dou t plus dou by dou x of q of x t rho if we expand this you will get this one. So you need to differentiate x appears here as well as in rho therefore need to differentiate q with respect to the first variable and differentiate q with respect to the last variable and differentiate rho with respect to x this is a chain rule. So chain rule is a very important rule that one must be very comfortable when you want to do anything with differentiation. So this is a quasi linear equation it is a first order PDE quasi linear because this may depend on rho that is why it is a quasi linear equation. Now we are going to model a highway where entries and exits are there in between that means we will see now how the earlier model derived is going to change. So the entries and exits are also called source and sinks in the PDE literature. So let us denote the source sink density at x at the time instant t. Now the model becomes this is the rate of change earlier this was just equal to the flux but now this will also have the sourcing term which is this integral a to b fxt dx. Now bringing everything to one side what we get is integral a to b of certain thing is 0 and this is true once again as before for every n b such that a is less than b both are arbitrary therefore the integrand must be 0 which will be the case whenever the integrand is continuous or local integrable but it is not unreasonable to assume that integral of over any set is 0 implies the integrand is 0. Now let us look at the how the first order PDE is appear in a mathematical context. So we are going to see an example consider two parameter family of surfaces. In fact what we are going to consider is surfaces which are graphs z equal to f of x y a b what are a and b they are some parameters varying in some intervals. So it is a two parameter family of graphs of functions. Now we want to derive a differential equation satisfied by this family and we are saying partial differential equation therefore what we can only do here is to differentiate this with respect to the two independent variables x and y and this is the expression we get. Now assume that from these two relations you can solve a as a function phi of x y z x z y and the b as a function of psi x y z x z y. Now question is it always possible these are all questions but here if it is possible we will go ahead and do the next step. What is the next step I am going to substitute for a and b these formulas inside this then what I will have is z equal to f of x y phi of x y z x z y comma psi of x y z x z y which will be a nonlinear partial differential equation in general. Now let us look at a specific example where the functions taken to be x minus a whole square plus y minus b whole square a and b are parameters varying in real numbers both of them are real numbers. Now what are these surfaces what does this equation represent? Represents cones family of cones. So differentiate this relation with respect to x and y and eliminate a and b in other words solve for a and b in terms of rest of the things. So here it is very simple a equal to x minus z x by 2 b equal to y minus z y by 2 now substitute the values of a and b inside this expression z equal to x minus a whole square plus y minus b whole square which is the equation of the family of surfaces. Once you do that and simplify you get this following PDE z x actually stands for dou z by dou x if you want to write in terms of x you can write dou u by dou x whole square plus dou u by dou a whole square equal to 4 u. Now let us see what are the problems which goes by the name of Cauchy or initial value or initial boundary value problems what they are. So let us consider a PDE f of x y u x u u x u y equal to 0 it means I am considering a PDE in 2 independent variables throughout this chapter we are going to consider first order PDE in 2 independent variables and then we will also say what how theory changes if you have one more variable. So x y are independent variables u is the dependent variable these are the derivatives. So there are 5 quantities here so f must be defined on a subset of r 5 and that we denote as omega 5 is a subset of r 5 and you have a function and then this will then define a partial differential equation. So what is the Cauchy problem given a space curve gamma in r 3 that means you are given a curve in r 3 which is described parametrically by this that is x y z equal to f s g s and h s as s varies in some interval i and f g h are c 1 functions on the interval i and such that the projection gamma 2 of gamma to x y plane where is gamma it is an r 3 so it will have x y z coordinates. Now you project it to the x y plane you will have x y coordinates that is x equal to f s and y equal to g s that is the curve gamma 2 s in c m i it is a regular curve what that means is f dash g dash do not vanish that means does not become 0 0 at every point of the curve if one of them is 0 other one is non-zero if f dash is 0 g dash is non-zero and find a solution to the PDE such that u of f s g s equal to h s for s belonging to a sub interval of i sub interval of i in other words a part of gamma lies on this surface s denoted by s equation is set of all x y z such that z equal to u x y on this surface a part of this curve given curve gamma lies right gamma coordinates are f s g s and h s third coordinate h s must be equal to u of first 2 coordinates f s g s that is the condition here we are not requiring that this should happen for every s in i we are only asking for s belonging to sub interval of i so this can be thought of as a local solution. So this gamma is called a data curve or datum curve or initial curve note that this problem actually makes sense only if gamma is subset of omega 3 what is omega 3 is a projection of omega 5 which is in r 5 to the first 3 coordinates x y u what is initial value problem it is a special type of Cauchy problem initial means there is something like a time in the problem and initially means at some particular time in the past something is happening and then you are interested in studying the equation for future times. So therefore one of the variables will have an interpretation of time let it be y there is no loss of generality in assuming y x would equally do the same thing so the y variable has an interpretation of the time variable and the datum curve now lies in the zx plane given by this x equal to s y equal to 0 z equal to hs in other words what we will be asking is actually u of x, 0 equal to h of x should be satisfied this is what we are asking for the for the solution of the PDE. So find u of x t such that u t plus 2 u x equal to 0 and u x 0 equal to sin x parametric representation of gamma what is gamma x equal to s y equal to r here t equal to 0 it is not y it should be t because y has a interpretation of time variable so you can as well write t so t equal to 0 and z equal to sin s and s belongs to r that is a parametric representation of gamma. Now we do not know how to solve this for now but given a formula we can always check that it is a solution so u of x t equal to sin of x minus 2 t if you quickly differentiate you will get that u t plus 2 u x equal to 0 it solves the initial value problem. So when t equal to 0 this formula u of x 0 what will we get u of x 0 will be sin x so initial condition is satisfied so we can think of like this so this is the time variable this is the u variable this is the time is x at t equal to 0 you are given a sin x like that so you have to imagine this in the ux plane and then at t equal to half what you will have is a formula from the formula what we have is it is sin x minus 1 so u of x, half is sin x minus 1 it just means the graph of sin has been shifted to x equal to 1 suppose this is 1 this is pi right so this is pi by 2 so this is 1.5 already so somewhere here so the graph will look like this is moving. So it is difficult to write for me in 3 dimensions but you should imagine that the graph of sin x has moved graph was like this at t equal to 0 now it has shifted to 1 but now this I am writing at t equal to half so just moves back. So okay now initial boundary value problems once again initial is there so there should be a time so the unknown u in this PDE x, t, u, u, x, u, t equal to 0 I already made this change of y to t because the word of initial y boundary so this equation or what you want to study it may not be relevant for all x in R it may be that it is relevant only for x positive or maybe for x in some bounded interval a, b in such cases imagine the first case if it is meaningful only in R plus then x equal to 0 is a boundary of R plus right boundary point and if you are studying x in a, b then there are 2 boundary points x equal to a and x equal to b at these points so you need to prescribe some conditions there that is what is called initial boundary value problem. Now let us look at a picture illustration so this is the case where the domain is R plus x belongs to R plus therefore you have boundary at x equal to 0 so you prescribe this g of course initial condition you prescribe. Now when you are doing initial boundary value problem when x belongs to this interval a, b you have to give initial conditions and also give boundary conditions. So now let us look at 3 examples 3 guiding examples for us Cauchy problems because you can understand entire theory by using these examples. Before that let us ask the following question does every Cauchy problem have a solution good question this question sounds like a very familiar question that we asked earlier does every problem have a solution this is not the first time we came across such a question it was asked many times and many times we even had a complete answer for example system of linear equations where a, x equal to b varies a square matrix there we understand completely and what conditions you have existence what condition you have uniqueness and non-existence. Now let us ask the same question in some few well known situations for us before solutions of polynomial equations in one real variable what about that a polynomial may not have a solution polynomial equation x square plus 1 equal to 0 has no real solution it can have exactly one solution let us say x minus 1 equal to 0 or x into x square plus 1 equal to 0 they have exactly one solution then you can have finitely many solutions let us take very simple x minus 2 into x minus 3 equal to 0 right any finite number let us say a 1 a 2 a n you write x minus a 1 into x minus a 2 into x minus a n equal to 0 precisely these are the solutions a 1 a 2 a n but you cannot have infinitely many solutions for polynomial equations that is because of fundamental theorem of algebra it says given a non-constant polynomial it has exactly the same number of roots as that degree counting multiplicities in the complex plane. Therefore in real numbers may be less than or equal to that then solutions to initial value problems for ODE is this is where we have seen Picard's theorem and Piano's theorem in Piano's theorem if the right hand side let us say y dash equal to f x y let us write once this is the kind of equations for which we have a theory and this is the initial value problem if f was continuous we had Piano's theorem which said there is a solution. In addition if f is Lipschitz with respect to the y variable then Picard's theorem told us that it has a unique solution and when you do not have unique solution you can easily show that you have infinitely many solutions that is the situation about ODE so this is under sufficient conditions that we have proved these theorems. So if these sufficient conditions are not satisfied we have no idea what will happen anything may happen you may still have uniqueness even though the right hand side function f is not Lipschitz that is a possibility. Now solutions to boundary value problems we have a Bernstein theorem under some sufficient conditions it guarantees that a second order ODE boundary value problem posed for that will have a unique solution at least from the Dirichlet data okay. This if you do not if you are not studied BVPs you can look at any good book on ordinary differential equations you will find. Then solutions to transcendental equation this is the most difficult one you know it is not like polynomials so you have to worry with each separate equation is a different story there are once again sufficient conditions okay. Now let us see what are the examples so the examples we are going to see are of Cauchy problems in these 3 examples which demonstrate all 3 possibilities in this case what are the possibilities you have a unique solution infinitely many solutions and no solution. Now of course another option is the finitely many solutions which I have not thought about let us take that up in a tutorial session that discussion. So what does this mean it means that we do not expect existence uniqueness theorem for free for any first order PDE we do not expect so only under some special assumptions in other words sufficient conditions we can expect such theorems which was true in all our earlier cases let us say in the ODE initial value problems or boundary value problems that is a true. Okay let us look at a very simple first order PDE it is Ux equal to Cu, C is a constant we will look at a special constants later C equal to 1 and minus 1 later on in the case of initial boundary value problems here C can be any number real number so it is posed for X in R and T in R you do not see T in the problem so it is actually ODE and from our ODE knowledge we can solve this any solution must satisfy this equation Uxt equal to U0T into E power Cx. Now let us look at 3 Cauchy data what are they first one is U of 0T equal to T second is Ux0 and here also Ux0 that means initial Cauchy data is given here on T axis here in other 2 cases given on X axis. Now using this expression we will get this U0T you wanted T is supplied so T into E power Cx that is a solution in this case Ux0 that is T equal to 0 that is U00 into E power Cx but U00 must be 1 therefore any function of T such that T of 0 is 1 we will do of job it will be a solution Tt into C E power Cx is a solution whenever T0 equal to 1. Here if U is a solution then what is expected is sin X must be a multiple of E power Cx that is impossible because sin X and E power Cx are always linearly independent as functions on any interval that you consider. So message is that Cauchy data 1 unique solution Cauchy data 2 and 3 one case you have infinitely many solutions for Cauchy data 3 there are no solutions so 3 possibilities have been exhibited here. Now the why the Cauchy problems behave differently PDE was the same Ux equal to Cu then what is different U was prescribed on T axis we had uniqueness and when U is prescribed on X axis either we had infinitely many solutions or no solutions therefore we ask the following question is T axis something special for the equation or is it X axis which is special for this equation the reason for the first question is because we have uniqueness second question is we have many possibilities so who is really special here because special people have to be taken care with a lot of special care we will see that later on. So the answers we will see later as we study the first order PDEs. Now let us look at a simple first order PDE for which we pose IBVP and a few observations we will not be dealing with this further in our course. So the fact is that general solution of Ud plus Cu X equal to 0 is given by Uxt equal to Phi of X minus Ct where Phi is any C1 function which is arbitrary of course what is that T equal to 0 Ux 0 becomes Phi X. So this Phi is nothing but the initial solution initial condition. Now initial boundary value problem as I told you there will be a PDE posed in the first quadrant Xt X positive T positive initial condition is given and there is only one boundary point namely X equal to 0 therefore U of 0 T is also prescribed. Now Uxt equal to F of X minus Ct because see here we said Phi is initial data right. So therefore here also we have initial data so how much we can this determines the solution. So F of X minus Ct will be a solution surely no problem but whenever X minus Ct belongs to the domain of F, F is defined only for greater than or equal to 0 therefore this determines the solution whenever X is bigger than or equal to Ct we will see a picture soon. Now on the line X minus Ct the solution U will be constant it will be F of K X minus Ct equal to K K is greater than or equal to 0 therefore this is formula is applies and Uxt equal to Fk it is constant. Now let us look at the case where C equal to 1 this is the picture. So this is Ux 0 Fx this is U0 Tgt and U in this region in this region this the line X equal to T is in dots to the right side of that this region corresponds to X bigger than or equal to T there F of X minus Ct similarly you can show that here it will be G of T minus X that will be solution. So on this line T minus X equal to K solution will be Gk and on this line X minus Ct equal to K solution will be F of K. So initial condition determines U in this region and boundary condition determines in this region. Now what about X line X equal to T what will happen? So let us write the formula this is the formula that we said now if this has to be a solution it has to be differentiable the first question is is it differentiable? So this is a candidate solution we say because we have derived certain possible formula for the solution that is why we propose a candidate we need to verify that it is indeed a solution. So that requires that Fg must be C1 functions and compatibility of the data is needed F0 must be equal to G0 F dash 0 equal to minus G dash 0. How do you get these compatibility conditions? You simply ask at points where X equal to T write down the differentiability property of U of Xt that will tell you that this condition has to be met otherwise it would not be differentiable. So once you have these compatibility conditions that implies that U has U is a C1 function and IBVP has a unique solution. Now the Kc equal to minus 1 is totally different now the line is X plus T equal to constant this line touches both the boundary as well as the initial data. So and once again F must be constant on this line solution must be constant therefore this line touches at K0 so it should the value on this line should be Fk and it touches here at 0 K so the answer must be the solution must be G of K. So on this line the solution is both F of K and G of K what if F of K is not equal to G of K there is a problem. This means that G cannot be prescribed independent of F. This initial boundary value problem has no solution in general but there are some generalized notions of solutions where under some other condition they admit solutions. So we will not be discussing such generalized notions this is in the normal notion of a solution there is no solution that is very clear from the formulae. So let us summarize what we did today we have derived a first order PDE to model traffic flow and also modified to account for sources and sinks namely entries and exits in the express way and we highlighted the roles of balance law and constitutive relations in deriving mathematical models. This is how models in let us say continuum mechanics will be derived these are the two things which are at the heart of any modeling and then through three examples we understood that number of solutions to a Cauchy problem depends on the relation of the PDE to the datum curve and then we saw IBVP problems need not have solutions. So thank you.


The one downside that proof of stake has over proof of work that's absolutely true and it doesn't seem to be resolvable in a theoretical sense is this notion of algorithmic weight. Proof of work when someone generates a block they have to actually do some work they have to expend energy to do this and as long as you assume the problem is hard we can actually calculate how much work is required to do. So when you look at a blockchain generated by proof of work and you have multiple versions of that blockchain A through Z you can easily pick out which one you'd consider to be the longest by which one has the most work to it. That's the idea of algorithmic weight. The problem with proof of stake is that there isn't an obvious way to synthesize algorithmic weight in a proof of stake system. So if you assume that the Genesis block is correct and that people stay synchronized with the network with some degree of regularity the system is completely secure from a theoretical standpoint. However in real-life use cases people have their cell phones they leave them on they off people have their laptops they turn them on and off they join the network they leave the network people are much more asynchronous. So given that you do need to have some notion of catching up with the chain and if you're given multiple versions of history you have to decide which one is correct. So what we're trying to do with Ouroboros and the Cardano project is to have theory meet practicality good engineering principles in common sense meet good models.


Hello students, I am Robin Shaw. Welcome to today's Livestream. Hopefully I can help you guys with your English questions Just give me a second. I'm gonna go to You're gonna post the link of this live stream very quickly to get some students here. I Always forget to post links You know Part of YouTube being is all this extra stuff and it's it's annoying sometimes I really need an assistant. So if you want to be an assistant Channel, let me know. Okay All right today Some of you are asking about the title the love episode. Don't get excited. That's called clickbait I'm not gonna talk about love at all So if you're disappointed, I'm sorry Did you come here to talk about love? All right, let's let's see the students here. I got my tea here Lolli Lolli. Hello from France. There is a special student that I'm looking for Every student is a special student, but there's one really special student today that I'm looking for and Maybe it's you you guess who it is Sorry Lolli Lolli you're a special student, but you're not the the special student. I'm looking for today Layla, how is your day today? Love episode? Okay, I love you Layla and I love all my students but Layla especially Layla, so it's a love episode because I can just say I love all my students But Layla you're not the special special student today sleepwalker. Hello everyone now sleepwalker You're the spec you are the special special student today Any any guesses why you might be the special special student today sleepwalker? Don't worry sleepwalker your family.  I Wish I was doing a live zoom. It's a sleepwalker right now. All right going down the list Let's see I'll see see all the other students here English hub for competition Tell me tell me about the pigeon pigeon is a is a mix of two languages So you can have I think there's a new Orleans in America they have a pigeon kind of mix French English and other languages Mixed together Frida, hello, you were on the live stream because I would did my Instagram live Yeah On Instagram, I did I guess it was political. I Don't talk about politics much. Don't worry sleepwalker.  I'm not gonna talk about Ukraine, but sleepwalker. I am gonna ask you has your life easy question, don't worry has your life been effected affected by What's happening in? What's going on in the world let's say that I'm trying to be nice has your life been directly affected Yes, or no And you can tell us how if you want Layla guess a special student Every student special but sleepwalkers sleepwalkers this is a special student this week Mald 8 NATO 8 Mald 8 ball. I'm trying to read that fast Mald 8 NATO. I'm not sure I'm gonna pronounce that good. Good day Welcome to the channel VJ. Hello. If you got any English questions Or if you want to talk about something let me know let me know Sleepwalkers the best student I didn't say sleepwalkers the best student special special special Come on guys English hub for competition do you preach? I Can't I can't speak English do you teach pronunciation? Yeah, I can teach pronunciation I Do know some pronunciation techniques how to improve some pronunciation now English for competition English up for competition. I'm gonna check your channel really quick. What do you what are you about? You got videos English hub for You don't have. Oh, is that you on your video? Okay, I'm not gonna You don't you don't really have many videos. So, okay Yeah pronunciation if you're I can see you maybe you're from India English hub competition India or Pakistan Are you worried about your accent? I wouldn't worry about your accent too much in this It's not so bad So English hub for competition is there any paid class I Don't I you know I talk to students every day. I don't like I'm free Most students don't have to pay me but you know, I do appreciate I Do appreciate the people that support my Tea budget which is and I really love those students and of course a special attention Well, my help is free if you're in WhatsApp you can ask me questions and today I did Today a Korean Student was in my group and they wanted help with OPEC test and I said hey, let's let's chat for a bit So we chat for about 20 minutes about OPEC So I Don't have I'm free and it's easy to contact me all I ask is you be diligent if you're diligent Let's see All right, I think Layla has her questions coming. Let's switch to the digital whiteboard Red we don't want red. I've learned that put up with someone. All right. This is our expression put up put up With some of let's not use red. Let's use green mean someone Means accept or continue so I tried to make the fall exists. I'm gonna yeah Put up with someone to put an equal sign means accept Or continue I'm gonna use the word Tolerate you tolerate someone. All right, so your example sentences. Oh Sleep walker reply we get to your we get the sleep walker the special student today in a moment Your example sentence You're one a few people who put up with me.  You got a few sentences There's no There's no elbow room to move these grumpy I'm not sure where the elbow room is that in the house Okay You're one of one of the few let's fix the gram here. You're one of the few people who put up with me Okay, so what that would mean you have put up with someone with me use green so It may be your personality is difficult. All right.  They stay all right.  I Can't put up with this house.  This house is not someone so going back to our definition We need a person put up with this house We wouldn't say put up with this house. We're gonna use another expression.  He's grumpy. I Don't know how she she puts up with him. Okay, so he's grumpy. He's kind of an angry guy So that's someone who's difficult to be around a grumpy person and I'm a grumpy person So I don't know how she puts up with it like she stays with him. She's always around him I don't understand how she tolerates that guy Okay So this is a good one and this is a good one, but for this the house is not a someone so I would use I can't stand it All right. Hope that helps And let's get to sleepwalkers It has been a it has been a very it has been a nervous week. We are all very worried and want everything to end faster and have negotiations, okay That's a general statement, but what about you directly sleepwalker any problem Correctly, I saw I saw in the news today lots of Russians going to the bank machine to get their money Did you do that too? kanjiya hello How have you been I've been fine Mohammed die die Ganon. Do you have any questions? Thank you. Good morning. What's good night to me? It's almost 11 p.m. Here in Korea Ramden Maui my connections unstable sir Robin That's too bad, I know everyone's Wi-Fi is different I Can't help can't help that. I hope you have stable Wi-Fi Hi, Robin. This is from Alex. I've been struggling to pick when to use rise and raise I'm going right to the dictionary just to Just make sure everyone Understands what I'm gonna say. So let's focus on rise Get the raise in a moment. Oh, I don't want to delete it. Here we go rice. Let's not put capital Let's get raised And everyone's gonna understand why this is difficult And automatically gets cattle. I don't want to put capital. All right. I got the words. I did my research I know the answer.  Let's look at the definition To come up or go upwards or something rise like the sun Rises Or to reach a higher level position or position. I want my score to rise raise To raise something you lift or Move something to a higher level. All right. So this is more of a Physical action I'm gonna raise you up onto the chair So That's more of a physical action What else do we raise? I raise chickens Which is grow chickens that can be raised, but that's not the raise you're talking about So the sun rises We I do not have direct power over that. Okay, I do not have direct power of that. That's gonna happen I do I'm not involved in that every day the sun rises. I'm not involved What else rises the temperature I I'm not God I don't control the temperature it's out of my power If it's outside If it's outside if it's in my house raise Let's let's highlight it with some other color I'm going to raise the temperature now I have the power and I I have the power to increase the temperature. Okay So I can't go through every example if you have more examples throw them at me But I'm gonna say rise is more of things going up that we don't have power over and Raise is more of I have the power to lift something physically or in this case the temperature I can physically turn the knob on the temperature That's the simple explanation and that's the quick and simple way. I have to move on to Sleepwalker what a sleepwalker half can we say that the word mesmerized quite close to the word entranced. Okay, are they synonyms? Good question and if I said I'm Mesmer I can't spell it. Is that how you spell it? Mesmerized I guess so I'm mesmerized by your beauty I'm entranced By your beauty Interesting I'm gonna mean very they are synonyms very very similar. Are they exactly the same? No No, so what's the difference is you're asking me? I just checking the spelling Before I give you my answer The internet has different ideas about the day. I'm doing a quick check of what other people said Different. All right. I'm just gonna say my understanding Which might be different if you talk to a different native speaker? Uh entranced I would say is more like a Spell from someone more a little a little bit negative I think both of the both of these can be positive sentences to say to a woman. I'm mesmerized by your beauty I'm entranced by your beauty So mesmerized I'm what what do these words mean like I'm staring my focus is on you I cannot move my focus to another place. I'm just focused on you and The entranced I would say is a little more like I don't it's out of my power or you're using some power This is a hard one. Where did you find these words? Mesmerized is more common. So the problem for me is the entranced When do we use entranced? Yeah, I'm just gonna say they're synonyms 99% of the time they mean the same thing. I wouldn't worry about it Let's move on. Right Robin. Nothing has been changed yet Yet, but there will be many sanctions from countries and prices will rise I think prices will rise in many countries. It'll affect the world We're all going to experience what's happening in that part of the The world's the walker. All right. Layla says when I make my sentences, that's not Layla's voice That's just the voice I'm using when I make my sentences. I didn't pay attention to the second one I can't stand this house. All right. Oh, okay. You you got it. You got what I taught Thanks for clarification Mohammed you said explain and emphasis and M M Classes Emphasize we're gonna use are the same meaning No explain is to tell the details about something and emphasize is to put more focus on something so Let me explain These are dictionary words you can check the dictionary let me explain the rules, okay So I'm gonna tell you about the rules. Let's say there's five rules. I'm gonna explain the five rules in my class let me Emphasize Rule number five or let's say rule number three So I will explain the five rules in my class. I'm gonna explain This is rule one rule two rule three rule four rule five, but I want to emphasize rule three I want to put more focus on rule three. I'm making rule three very important All right, so more power to rule three Do you ask your boss for a pay rise or pay raise you ask for a pay raise because they have the power they have the power to Give you more money you ask for a pay raise Sleep Walker Two phrasal verbs Per cup Liven up Ginger up Cheer up You'd absolutely the same Well, I've heard perk up live enough cheer up. I haven't heard ginger up. So maybe that's a British expression Let me check that really check Ginger up Ginger up Never heard that that's British. Okay. That's why I didn't hear it. So there you go This is British definitely British English. Do they mean exactly the same? Yeah, they're synonyms Absolute this absolutely is 100% no This show I never say 100% Let's go for 99% There might be You know different situations You know, if you're in America, you can't say ginger up. They won't understand. I won't understand in Canada.  I guess could be used more about Your energy level Get more energy per cup is more about your emotion Could be energy Like get happy get more energy live and up Get more energy and cheer up is more just about emotion and the ginger up is about Yeah, that would also be Emotion or energy So again perk up emotion Smile be happy energy Don't be Perk up, you know get some energy Live it up is more about just get energy Excitement and ginger up emotion your mood and energy and cheer up is emotion be happy cheer up Okay, so very very very similar. I wouldn't worry about those but very close is Put up with someone a common phrasal verb do native speakers use the answer is yes And I I can say 100% to this Everyone here you should know put up put up with someone. I have to put up with I have to what do I put up with I have to put up with my name neighbors barking dog why am I This is not true. I might my neighbor doesn't have a barking dog It's just an example now parking dog is not someone it's It's still a living thing so we can use a dog. So I have to put up so every night Again, it's not true. It's just an example sentence every night my neighbor's dog And I cannot do anything about it. I Do not have the power. So I have to put up. I have to endure. I have to tolerate. I have no choice Yes, we use this expression every native speaker uses this as expression and You should know it we hello Ibrahim the yellow hello from Seneca all Sleepwalker. I like beautiful adjectives Well beautiful as an adjective Michelle hi, I'm here So we have both both top students from France here today Michelle and Lolli Lolli Michelle Michelle and Lolli Lolli sleepwalker So sleepwalker Robin So I'll fix your question first. Did you know? Did you know? We're asking the question will keep your present tense. Did you know? Well, this will be past tense Did you and then no Present tense. Did you know about Dunbas before this week? No, I did not but I think the world is learning in the next week's months the world will learn about all these places and the history and You know propaganda from both sides, right? Both sides are giving propaganda And fake news, so we're all gonna learn whether we want to or not That's what's happening in the world sleepwalker. You might be the Special student for a long time Hello win Opic test is related to study abroad. I Don't know much about the Opic test. It's just a speaking test Salty cheddar 72 salty cheddar says Ginger up in America would take it to die something red. Yeah Yeah This ginger is ginger up. Hey, you should ginger up Yeah, that would it would be strange if someone said that but we might think yes make make something red That's an interesting calm common salty cheddar Yeah, you can't say ginger up to an American or Canadian You can beat blues. What does it mean? I often hear blue words such as blueprint these days blue meaning looks like positive Well, blue there could be a lot of expressions with blue and This is gonna be you can beat the blues Blue is a symbol of sadness Or depression so you can beat the blues you can overcome your depression So the blues let's change this to blue so blue is a color But it's also word that means sad or depressed and the blues means sadness or depression So you you can beat the blues would mean you can overcome your depression That's what I I that's the only thing I know about the blues Now you hear there's other words with blue and you're just saying blueprint. That's a different word Blueprint is kind of a plan Building plan. That's a noun. That's an actual piece of paper that is blue Blue meaning looks like positive. Well, no in this case blue if someone is blue. I'm blue today Someone said I'm blue today Yeah, their skin is not blue They they are sad. They are sad. They are depressed. So it's not positive. It's a bad thing win Are you blue? Well, very quickly red Might be a Color of anger Anger red his face is red or his You know, something's red But you didn't ask that so All right, let's get a question Could you check the following tag questions? Okay, let's take a look Huh No, no, you did this wrong again, right? I was confusing one. I gotcha All right, you got three here, right? She these are tag questions. So the questions are at the end She hasn't cleared the boss's office has she so we have we're using has and she So you're correct has she this is correct This was good. She hasn't cleared the boss's office has she So that's how you say she hasn't cleared the boss's office has she All right, I am not a teacher are I no This is gonna be am I'm not a teacher am I? So this is a noun Why is this one confusing? I don't remember what the take question we had before with I Let me just do a quick check take question with I am Bring some tea Yeah, I don't remember the last The answer was aren't I But I don't remember the question see I'm your I'm your friend Aren't I okay, this could work you had a am I You didn't eat your dinner yet. Did you that's correct? That's correct. So you don't have problems. It's just the I So I'm your friend aren't I I'm not a teacher am I Why does this use aren't I now why does this use am I I Don't know the rule This is what's confusing. I know it's confusing me too because I know the answer But I don't know the rule. I'm gonna check my assistant teacher Google Very quickly to see if someone else smarter than me Figured this out. Okay. Well, I think I figured it out myself. You got a negative here Let's not make it right this because the aren't I I think I figured it out equals Am I not? So I'm your friend Am I not is it's the same as aren't I but here you have not So I'm not a Teacher am I yeah, so I'm gonna say that's the rule because you have a negative here It's am I you don't have a negative. You're using aren't I which means at am I not? Okay? Give me some more practice that break Prove my theory right or wrong. Give me some more examples. You got another one here. I Work hard every day. Don't tie that's correct And you had the question that's correct Rita What you got going on here for Rita?  I'm a geek the big paradox. I heard it from a kpop song. What does the sentence mean? while kpop They have What it's called conglish? Which is Korean English? Which means you should never be learning English from a kpop song because their English is wrong And I'm just gonna check the grammar of the lyrics I can't play this song because YouTube will copyright the video if I play this song So hold up. Yeah, I'm a geek the big paradox That's not proper English That's not English. It's just words in the song. It might have a meaning. I would have to listen to the song But that's not proper English a lot of kpop songs do not use proper English Do not learn or study English from kpop songs. So I am okay. I Am an English student aren't I yeah, that's right. That's right So if you made this negative I am not French student Am I I'm not a French. We got the negative. So we use am I? In Zen so gala so hello, I guess white color Prefers no refers to peace Uh-huh. Isn't it? No So if you're writing a question is the white color refer to peace If you're not making a tag question, you're making the question at the beginning you're starting with is No, the question should be does the white color refer to peace and So if you're making a tag question, doesn't it? Cabinu. Okay. Let's see what you got Little sick today headaches Hi, sir, I couldn't be here for a long time because of my illness. Okay, that's too bad I haven't been feeling well because of the fever. Oh, do you have COVID you got an omicron? Have you know that's Sort of hear that man Take some rest get some rest. Don't watch me Go for a peaceful walk or Don't look at the Video displays and things like that. Just relax Yes, don't if you got COVID don't go out for walks with other people. I am not a nurse. Am I I'm not your assistant? Yeah, I am not a child. Am I yeah, that's all right. We got it. I think we solved that Sleepwalker, what if the question have you heard about it before? Have you heard about it before I had told You can see these blue lines in Google saying that's wrong and my brain saying it's wrong or have you heard about it before? I have told Should we use present and past perfect the questions of what questions is correct? Have you heard about it before?  Well, let's focus on have and had you can use both You're gonna see native speakers using both, but I guess because you have two Time-references it should use had okay.  No Well, yes, I did hear about it before before you told me, but I didn't hear about it before a week ago Didn't sleep well feel terrible. She said God. I can't figure it If I can't figure it well Should be a in Google agrees with me should be I can't figure it out. I Can't figure it You know figure means bear it figure it. I don't know. I I have no idea what that means I don't have enough information lay lay less. Sorry. I don't I don't know my guess is I Can't figure it out I'm gonna take a guess Which equals I don't understand why In this case Can't figure I can't figure it. So this person for whatever reason might just be shortening that expression and They they just means I don't understand why So they're very hungry So they didn't sleep well and they're very hungry and this might mean they don't know why Yeah, I got a headache every day lately So past perfect past simple. Oh, you want the exact grammar terms?  Hello teacher and mates Hold the line Vincenzo has a question about an idiom. Yes, that is an idiom Which means?  Hold the line Sleep we're gonna rub you still dizziness sometimes. Yep, still dizzy sometimes Well, we're not here To talk about my health We're here to talk about English excuse me figure out Has means phrasal work. I'm not sure what your question is here, but is figure out a phrasal verb. Yes Figure out is a a phrasal verb figure out find the solution. That's a phrasal verb Okay, Mohammed, I'm living in Seattle. So what do you say? Hello teacher Robert Shaw. Can you Please tell me a time the class is starting in Korea. I'm living in Seattle. Well We go back That's 13 30 GMT that I believe that's london time. What's I live in korea Which I start at 10 All right time 10 30 p.m at night. That's one my live stream Why did I choose this time? You guys can't see it So korea sunday 10 30 p.m. Why did I choose this time? because When you're doing a live stream you have to choose a time Guaranteed you will never be busy So for example, if I chose a time Saturday My time like 8 p.m. Well, it's possible saturday. I go out. I meet my friend or I have a late dinner or you know So this time I cannot guarantee this time. So I had to when I started a live stream. Okay. What time can I guarantee? sunday 10 30 p.m another problem is Korea lives it. We're in the future. I live in the future I live in the future Right now it is 11 21 p.m Uh sunday 11 21 p.m. My my sunday is almost finished and for a lot of you Your days are beginning So seattle So I start sunday 10 30 in seattle america Is sunday? 5 30 No saturday no sunday I'm confused 5 30 Yeah, seattle would be the worst place To watch my live stream California would be the worst place. No, hawaii would probably be the worst place I don't know is hawaii If I look at time zones Just quickly looking at time zones here Hawaii is right now hawaii is 4 30 You would have to start watching my live stream at 3 30 a.m So hawaii seattle these this is the worst places in the world to be watching my live stream But I don't really need to teach people from america. So it's not it's not a big problem So anyway to answer your question. This is when I start my live stream in seattle your time Sunday 5 30 a.m Ouch wake up early for this Good luck Farida I freak out easily Is it correct? Yes I freak out. I get upset or excited easily If I want to say don't work hard that might cause you to feel exhausted. Could I say you shouldn't stress yourself? I would say well, you can say this The grammar is right and you can say this the grammar is right, but I'm gonna say you're not my mom I don't work hard. I don't get stressed out. You don't know me Robin, I knew that if there's a before after it is not necessary to put to use past Perfect because the order of the actions is clear Depends on the sin. I got to see the sentences I don't know every rule you might be right, but Show me the sentences Example sentences I heard yesterday you can say it again Oh No, it's not can you you can say it again you you can say you can say not it The correct expression should be that Uh, it's possible you might have heard it, but More common is you can say that again Which if someone says you can say that again Which means I agree with you So yes that that You can say it again means Means repeat yourself So this is the common way that we understand this sentence. You can say it again. You can repeat yourself Okay, but in English what sleepwalker is talking about is we have this very special English expression only spoken Sometimes when people say you can say that again It means They agree with you. So let's Give an example sleepwalker is To else Sleepwalker is awesome Yeah, let's not use a robin says sleepwalker is awesome. And then leila says You can say that again And leila is just saying I agree with you Where are you broadcasting from i'm broadcasting from kwangmyung korea and if we I hope the stalkers are not watching me right now. Please don't come to my house and kill me We're gonna pull up a map of korea You can see that map Here is korea Here is soul Well, you know, I'll go out farther so you can see where we are in the world There's leila and sleepwalkers here and lolly lolly michelle there and uh, a lot of you are from india, but i'm over here This is what i was talking about. This is the international date line. So This is where the day starts and it goes and this is where the day ends. So hawaii, seattle Terrible, it's all right wrong screen. All right All right France lolly lolly michelle leila um And sleepwalkers up here. I'm here south korea we zoom in There's soull, oh there's the date line. I live in the future Only tokyo and maybe new zealand is before me Zoom in the soul zoom, zoom, zoom, zoom zoom zoom zoom zoom zoom So there is Seoul, and Seoul is a big, it's a city, but we also call it a metropolitan area. Metropolitan area means all this, it's just one large city. So you can see this is one large city. There's about 25 million people living in this area. So it's all connected by the same subway and roads and whatnot. So if I move into Seoul and down here, you see a little place called Gwangmyeong. So we're gonna zoom in here, Gwangmyeong. So Seoul, the official border of Seoul is right here, but it's just one city, it's just one city. And I'm down here. So this is my area and then if we put the boots on the ground, this is what my neighborhood looks like. These are just called villas, villas. And I live in this, no, where do I live? I live in this villa. It's an older picture, this business is not here anymore, but I live in this villa and that's my neighborhood. Why did I do all that?  All right, so broadcasting from Korea. Win, is it silly if I chat with a broad friend simply as much as you can say I have no, just keep chatting, win, just keep talking. Whatever you say is good. Just keep talking. All right, everyone's telling me they're time now. 5.20 in Saori, Costa Rica, 8.20. That's early two on a Sunday, win 8.30, 8.53 p.m. Scotland, oh, 2.30, 3.30. Oh, Adan, Khabdi, hello. Hello, welcome, okay, not Robin's mom, am I? You're not, I don't think you are. Maybe you can check that on your own time. I'm not gonna explain that. Somalia, okay, that's good.  You have to do 10 push-ups, so do we film yourself doing 10 push-ups? Send me that video in WhatsApp group. Sleepwalker, it would be nice if you would have a walk and stream. Well, Sleepwalker, I keep thinking, I keep thinking of that channel you showed me. That's hard because that requires a little bit of equipment, it's not. It's so easy. I wanna do that, I wanna do that, Sleepwalker, but I'm always, my phone, my phone is old. The main problem is I would use my phone and my phone is old. So this phone is about at least five years old. So the battery dies in, if I was doing a live stream, the battery would die so fast. But the Sleepwalker, that is my dream to do that sort of live stream. I'll think about that more. Great, have you ever heard about the chicken soup book? Yeah, we have a, it's called chicken soap? No, soup, not soap, chicken soup for the soul. So that's a book series, there's a few books, they're positive books with positive stories. I know they would be good to learn English. If you checked out these books, if you ever saw these books, I think they would be pretty good material to study English. Actually, let's see, I'm just gonna do a quick check. That would be good material. Cause those books are basically positive stories and everyone wants to hear a positive story to show Korea. Okay, Sleepwalker, yeah, push-ups. That's, late students have to do push-ups. Do we, I expect, what, ha ha, sorry, what did we say? Ah, sorry, teacher Robin, don't give me, because you are not listening to me and you're complaining about your punishment. It is now 20 push-ups. Do we, do not complain, I will just add to your punishment, 20 push-ups for being late. Oh, Lavi, you're late, 10 push-ups. When you get a new phone, please do outdoors live stream. Well, the other problem is I do live streams at 10 p.m. or 10 30 p.m. my time. It's night, it's dark. You can't see anything if I'm, sorry, not, not, not. You can't see anything if I walk around, it's all dark, so what I would wanna do is I would go to Seoul, a more interesting area, and do the live stream in the more interesting area. But I'm worried about the people around me, because I don't wanna be bothered by people jumping in the live stream. Yeah, I streamed in the past in my area before, but it's so dark and noisy and wind by using Power Bank. Well, wind, you're, again, the dude, those kind of like high-quality live streams requires equipment and good equipment requires money. And I'm thankful for the people that support this channel, but there's not much money in this channel. I might, I'll think about it, I wanna do it, so we'll see. It's coincidence, but right now I'm preparing chicken soup. That is a coincidence, that is a coincidence. All right, I'm gonna finish up in a few minutes here. I'm looking at the time down here, 11.36 p.m. It's about the time I get tired in my live stream. Hey, teacher Robin, may I know about your family? How many family members siblings do you have? I'm sorry, I have one brother. My parents already passed away. Do you think you're on the live stream? Okay, 20 push-ups. I'm reading the comments and I'm getting tired, so I'm not gonna respond to everything. Just the questions, Mohammed, Diagana. Hi, teacher Robin Shaw. How can I join the WhatsApp group? Excuse me. There's a link somewhere on the channel. Look around, maybe under the video in the video description. Join the WhatsApp group.  I get a lot of people and Mohammed's a common name. You can't just come into my group and say, hey, Robin, I'm Mohammed. I got a thousand Mohammed's. You gotta say, I'm Mohammed Diagana from your live stream and then I will put you in the special group. So I think the link is under every, there's ways to find the WhatsApp group. I put the links everywhere, just find me out. All right, and then here, everyone's saying thank you, thank you, thank you, thank you. All right, thank you, or Ventus Sislav. Are you working as a English teacher in Korea? Yeah, I'm a English teacher at a university here in Korea. Palavi, I'm doing well. I'm just about to end this live stream. Let's go to full screen and let's move the comments. Coming to the end, I'm not gonna do any more questions on the whiteboard. We didn't see Alyssa today. Actually, I'm very happy because we saw Dewey come out. Michelle was here earlier. I'm not sure if Michelle is still around. We had a lot of the members come today, so I'm very happy when I see the members here. We didn't see Jonathan, we missed him today. Thanks for watching. What's happening in the future? Yeah, I'm seeing if I can travel. I wanna travel in the future. So the earliest I can travel is July. I don't think I'm gonna be able to visit Russia Sleepwalker, but I might be able to come out and see Leila. We'll see how the world is in July. And Myanmar, I might not be able to see you on this trip. Where else can I go? I might be able to go to France if Lolli Lolli and Michelle are open to meeting me. I'll go to France to see them. Adana, I'm from Canada. Dewey, Indonesia. I went, I've been to Indonesia once, as you might know, I went to Jakarta and Bali, and I would like to go to Indonesia in winter vacation, not the summer vacation. So Dewey, wait one year. Cause I don't wanna, I usually don't spend winter in Korea. Usually I travel, but because of COVID, I've had to stay in Korea during the winter time. And I know you guys are thinking I'm Canadian and Canada is very cold, but that doesn't mean we like winter. I don't like winter. I wanna get out out of Korea during the winter. So Indonesia looks like a great place for me to go for the winter. So I'll go to Indonesia and stay with you, Dewey for two months, okay? In your house with your family. All right, Leila, okay. Okay, Lolli Lolli invites me to France. So every time I meet a student, that is your test. That's your English test. When you actually meet me and you have to speak English with me, that's your real test. That's more important than an IELTS test. And I've only met two students in my life from YouTube. Like they knew me on YouTube and I met them offline, only two students. One was Gerson in El Salvador and the other was Grace in Korea. But I hope to meet someone. Oh, Joshua Malay, welcome to Tanzania. Well, hey, Joshua, please be my friend and please talk to me more. I would love to go to Tanzania.  Costa Rica, I've been there. It might be, I won't be able to go back this year to Costa Rica, but certainly in the future I'll return to Costa Rica. Kuwait, sure. That's doable, please. Sure, I'm so glad to accept you to live with us. So Dwi, I'm there and I can punish you directly and do your push-ups now. I'm watching you. Maybe I'll have a little stick. Study English, don't be late for class. Michel, sure, France is a good choice, yes. Well, certainly I'll come visit. I'll see, you know, it's hard because Korea is going through its worst time of Omicron right now. Almost 200,000 people a day in Korea. Actually, about 160,000 people every day in Korea that's about, we're trending for 5 million people a month. Doesn't look good. My next semester is online. Doesn't look good. So I don't know when I'll be able to escape, but I'll try, I'll try. I really want to get out of here for the vacation time. Okay, thanks a lot for watching. I'm getting tired, getting late, almost midnight, so I'll see you guys again next week. Please continue to study English, do not give up in English. You have time every day for a little bit of English and please search out the WhatsApp group. Tell me in the WhatsApp group that you watched my live stream. Tell me your live stream name because I know your live stream name doesn't always match your WhatsApp group name. So you gotta tell me, hey, I'm such and such, I'm from your live stream and then I'll be able to help you a little better than the other people I don't know. Okay, bye everyone.


It is important to understand that although NM as we know is there as a mechanism to allow the availability of telephone numbers but it is also important to appreciate how the market has adopted NM and the journey that NM has traveled to become the de facto standard for the NGN. So we'll start with the drivers that led to the emergence of NM as an acceptable mechanism and then we briefly discuss some security concerns that surround NM. First the backward compatibility. For sure users continue to have telephone lines, mobile phones and hence the telephone numbers. So the telephone numbers will not go away and would remain as key identifiers for at least the telecom services. The increased use of NM actually is an excellent way to prolong the lifespan of telephone numbers. It means that now we are not looking at telephone numbers as something that we would like to shelf, instead we are looking at it as something that will stay with us and that is going to give us due services and functionality. As far as the number plans are concerned if you recall once we were using pure telecommunication assigned numbers they were quite rigid and they were based on the localities and the suburbs where we would reside. Here because of the convergence to IP there is an increasing detachment of the number from the location from the group of users from the services that were tied to the telephone numbers. So there is a need for increased flexibility not only with regards to the options that are associated with the telephone number but also with the numbering plans which the users seek. So if there is no flexibility on the user end to have a choice to select a certain kind of telephone number it means that the user would always try to seek an alternative and nobody would like to do that. So consequently the telecommunication service providers are increasingly trying to make flexible numbering plans. With a telephone number it is also important to understand that if we have one single telephone number and against that telephone number we can have a variety of services that we can associate that would further make the telephone number critical and important and it's going to stay with us. Then another important issue is the personal allocation to end users. Typically we saw that in the typical households there was one telephone number per household but with increasing flexibility that the users demand each individual user might be as well interested in having a telephone number of his or her own while residing in the same household. And lastly there is always a requirement to have a flexibility to have the telephone number that can be ported between services. So it means a single telephone number can represent any service at a particular instance of time. Now let's understand what has been the most important area with regards to the adoption of Inam. First of all Inam started getting significant attention and interest when voice over IP based applications and services were introduced in NGN. And there's a reason for that because voice over IP services are usually independent of the physical location and are also independent of the household or the per household basis. So the overall drivers that we saw in the last slide are very much applicable to the voice over IP communication scenario. Likewise the new voice over IP carriers actually try using this Inam along with SIP as an alternative to signaling standard 7. Signaling standard 7 as we all know is the signaling standard for the PSTN and PLMN networks. So in SS7 there's a dedicated network that comprises certain nodes which allow the transmission of the control signals. So with this emergence of Inam, we can now think about integrating it with SIP to do us the functionality what SS7 used to do alone. Because of the variety of Inam that is both public and carrier, some security and privacy issues do emerge. Especially in public Inam since an individual user is at liberty to reveal or associate virtually any information with his or her telephone number. So a whole set of interesting privacy and security vulnerabilities emerge. Of course, this data gets published on the internet. If it is with regards to an individual, it is risky for that individual. But if it regards to the carrier Inam or aka the infrastructure Inam, the problem is more significant because now we are talking about peering carriers that are exchanging information between each other for a group of users. So the solutions are not limited to, but solutions are related to authentication and authorization mechanisms that are overlaid in DNS, something called DNSSEC or DNS security measures. It is currently beyond the scope, but it's always an interesting way to explore what DNSSEC is about with regards to the Inam security.


Yeah Okay, hello, my name is Vladimir Ilistratov I haven't honored to be the last one today my talk is titled Prokitektura a procedural approach to create architectural 3d models Most of all the stuff I'm going to talk about can be found on This github repo including the source code of the add-on and the tutorial So what is Prokitektura? There is a version that it has a Greek origin Like this and it means programmable or procedural architecture. So how does it work? Let's pick up a building footprint and pick up a set of Python functions and produce a 3d architecture model and let's go ahead and see it in Blender So we set a set of Python functions here We selected a building footprint and now pressing apply Prokitektura rule So it must be textured You're like this We can play with some parameters like changing a height a bit or changing Floor height that's too much probably and so on It's possible also to change colors Let's use yellow instead of boring great one. So like this So few basic facts about Prokitektura a Set of small Python functions is used to generate a 3d model of buildings Those Python functions are called Rules each subsequent rule refines the model and adds additional details and Prokitektura was inspired by CGI shape grammar developed in the Federal Institute of Technology in Zurich and currently is used by Software S3 city engine has anyone heard of S3 city engine Yeah, okay, so that's rockin progress and the goal is to be able to Code the most of existing and ever existed buildings with Prokitektura So let's consider an example rule set We start from import so pro is short for Prokitektura Then we define some parameters. We seen these parameters in the example I showed you just a few seconds before it's height floor height and so on and notice that that we use here a function param if a Parameters wrapped in this function It means that this parameter could be accessed from outside and change interactively as I showed you just a minute ago also notice that height is generated randomly between 20 and 40 and Roof color Is not a parameter that accessed from outside. It can be accessed from outside. It's just a normal Python variable So let's continue Well, let's start from building footprint and the first rule is normally called a lot We perform an extrude to the specified height And the execution is passed to the next rule called building So let's examine the next rule called building and here we perform the composition a Front face will be processed by a front side rule a side face In fact a number of side side faces will be processed by side facade rule and the top face will be processed by the roof rule So next consider Front facade and side facade rules Here we apply a texture we specify a path to the texture and its width and height in the Global coordinates or in the real world coordinates. So one can say that this texture is 50 centimeters width and 50 centimeters height in the real world coordinates and This texture will be inherited by all a rule by all child rules and less over and less overridden by another texture or material That would be home then we perform a split in their vertical direction So we cut a ground floor it will be processed by the ground floor rule and We cut a number of we perform a number of repetitive splits. That's why we have here a repeat function and each Cut will process by the floor rule But what is the size of the each cut is it a floor height? Not really we have here a fl t Function it means floating size so in this context repeat and fl t combination means Cut the remaining space for the whole number of Cuts yeah, so the total number of floors will be a whole number not like 2.4 like this it will be a whole one. Yeah, so on the side-by-side used for Side faces it's looks nearly the same but instead I apply here a boring gray color instead of for the texture So let's continue Next we process the ground floor and Therefore we have the ground floor rule. We override the texture with another texture it's has We specify the path again and we specify its size in the Global coordinates and then we perform a Split and this time the split is performed in their horizontal direction so We would like to have some margin on the left and on the right and it's this margin will be processed by sidewall function Then we like to have an entrance on the right and The entrance has a floating size Therefore we have a fl t function and the entrance will be processed by entrance tile rule and We cut the rest and gave him have here repeat if cuts and there will be used for windows and processed in the tile rule So next we cut the entrance door and the windows so Let's consider their Tile rule So here we perform a split again in the horizontal direction our window will have the width of two and The remaining space Will be just preserved for the wall. We have here no rule specified and all Materials all textures from their parent rules will be inherited in for this case So then we cut some Then we process this rectangle used for the rule used for the window and The bottom Cut it again and this time in the horizontal direction the bottom part We cut the bottom part then cut a window the window has a height of 1.5 it will be processed by the window rule and the rest And the rest just we just we have here no rule and the all And this piece will Inherit all materials and all textures from the parent rules and the entrance tile used for the Entrance door is nearly similar we cut here a door So let's go ahead This rules are quite small and here just a sign A texture but notice that for The door and for the windows we don't assign a much size It means in this context that the texture will occupy all available space And here we substitute Their texture is another texture and specify the size for it so here how it looks like and Interesting feature that the same rule could be applied to an arbitrary building footprint and This leads us immediately to an interesting application. That's the city generation we have a city a set of Building footprints for a city or a part of a city and we apply for each footprint the same or specific set of rules So and generate a city. So let's take a look at the demo Have prepared the text a while. Here's our city. Let's see it rendered Let's go back to our presentation So another interesting application is So what could we do with this city? I attempted to bring it to the web and So I placed the city in a webGL virtual globe provided by CISU and JavaScript Library so for that I have Had to perform the conversion from Blender to Colada and then to GLTF format So JLTF format is a emerging format specifically designed for WebGL applications. It's developed by the same organization that recently developed Colada format so don't mentioned in his keynote speech that webGL viewer or Player is important for Blender and I think direct export and import to and from JLTF is also quite important as that JL is Getting in momentum So I'm not sure the demo because if both Blender and web browser are open then they're slowed down so and let's go back to our city demo so it looks like a Relatively detailed model he see here we have each Each window and each entrance door card In the building so What about baking so this city model could be used in interactive applications beat webGL application or a game I Realized the baking in the following way so one supplies a rule set for the high poly model and one supplies a Rule set for low poly model in this case. It's just an extrusion just extruded footprint And then the baking the texture baking is performed. So let's see how it works. I specified high poly Rule set and low poly rule set and place and press bake button Text a while So let's see how it looks like I think it's quite easy to see that it's Low-quality texture and let's see the baked baked texture is our baked texture output of baking texture baking So another interesting application is parametric modeling. I already Talked about it meet a bit. So we specify some parameters and we use a Function param to say that this parameter should be accessible from outside and changed interactively so I Code it a model from a real-world model it exists in the reality Let's see it So this building exists in the reality. I tried to call it it with 26 parameters So let's play a bit with them Change something it's too much and so on. I think the idea is clear So the set of parameters could be quite arbitrary and so interesting and one could tweak a model as He or she desires and that's our model. How it doesn't perform as it doesn't work Stamely so it crashes from time to time. I have to find out what's the reason of the crash So that's basically what I have realized so far now would like to talk about Work for the current weeks or month So what about the roofs you probably remember that the top face of our Example should be processed by the roof rule, but I actually Didn't show you anything about the roof Because it hasn't realized so far for that we have to specify To find a good specification for a roof function and then we have to implement it well, I can propose a specification for the roof function only for simple cases and for For complex cases it should be We'll have to think more about how to specify it. Let's say we have a hip hip truth and We have a height so it could be specified in this simple way and the same for gavel truth however It's not often that's Roof size that's simple. We often have very complex a roof shapes and the good specification should be found for those cases and About a few words about the permutation. There is a algorithm called straight skeleton used to solve roofs and it's already It's already developed in the insert polygon Provided by hover tricky so it would be good starting point. However, it doesn't work in every case Let's consider an example Yeah, that's simple footprint However, it's not that simple for the straight skeleton algorithm So I press insert polygon Let's add some height here and see what's going on Simple footprint. However, this case is not that simple for the Adon Should be investigated how to how to fix it and So it can be used for Prokitektura in other direction of rock could be simplification of Prokitektura function currently I have that complex structure decompose then parentheses then Dot then in true It's Related to the fact how Python processes how the Python works However, I think it's possible to do it like this In simple in simple way. It requires some digging into Python machinery However, without going to Python source code and the same for split function We have here in two in two it could be simplified like this So I'm close to finish How could you contribute try to code a building with Prokitektura and give your feedback How to specify implement roof window door balcony stairs and so on functions How to specify implement the different facade Decoration functions. So thank you for attention. Everything could be find on this github repa including the source code for the add-on and Tutorial and also there is a threat in the blend artist dot org Thank you. People have questions that can come down where we will close the day session now People can have a drink or go out or have dinners There are two Screenings of the Susana festival one at 7 and one at 9 30 There will be the same screening so simply pick one of them You can go out now first and have food come back at 9 30 or stay here a bit and watch it at 7 Thank you and I see you later You don't from check the public I have a question regarding your presentation Not all the buildings become people So you can then change, even if you grow the whole building, the whole city.