Well, if this course is a cake, then there are many ways to cut the cake. One way is to cut it along the lines of methodologies and this is the same table we showed early in lecture zero and also in the road map part of the textbook. Now we can view the language I've been using, which is mathematical in nature, as part of graph theory, optimization theory, gain theory, or learning theory. And these are the 20 different questions and chapters coming from different kinds of works. Now, but the bigger picture here is that we, on the one hand, would like to bring engineering to the so-called network science field by advocating the importance of domain specific functionalities. It's not just about topological properties that are universal across different networks, but also about specific, domain specific functionalities. On the other hand, we also want to bring networking principles to engineering curriculum and this provides what I think is a modern view of engineering education. Now, there are also other ways to cut the cake, for example, by looking at the concepts here. Okay. We see concepts such as aggregation and influence models, distributed coordination, feedback control, strategic equilibria and all these are very important subjects. They capture a lot of great ideas and we saw some of those in these 20 lectures across different networks. And if I have to provide another list of 20, not just 20 questions, but 20 top concepts, then I'll say this might be a list. , the top five, I'll say resource sharing, opinion aggregation and consensus formation ideas, positive and negative network effect and then, the wisdom and fallacy of crowds. Okay. One is independent, one it becomes dependent. We saw the idea of functional hierarchy, say layering and spatial hierarchy, say overlays from local to global. This has been a recurring theme in almost every single lecture and we also saw the trade-up between overprovisioning capacity versus overprovisioning connectivity as a kind of resource. There are also other interesting methodological concepts, such as the use of feedback control. The idea of utility maximization model. The use of network protocol, the importance of signaling, the idea of randomization, whether its randomization in Google PageRank or randomization in a random access in Wi-Fi networks, as well as mathematical modeling concepts, these are not just languages and hammers, but also ideas, such as the idea of consistency on a graph model. You model something as a set of nails and links, however you define them, and then you think about the consistency model. Think about strategic equilibria across intelligent agents You think about generative models, reverse engineering, latent factor models the low-dimensional model of a high-dimensional phenomenon such as watching movie and starting with axioms. Well, it has been quite a journey, I have to say, and as they say, that it's not how much you cover that matters most but how much you uncover and we certainly covered a lot, but uncovered perhaps even more. And it has been a lot of work on your part and on the part of the teaching staff. In particular, I really want to highlight the great contribution by the TA's Chris Brinton, Arpan Ghosh, Michael Wang all of them have provided so much help on the way. they didn't have to do this in the first time experiment of this course. among the six Princeton pilot courses on an online context, but they did and kudos to them. Now, this has been an experiment, as I just said, and as in all, all experiment we don't know the answer until we carry out a few more rounds it took more than one semester to stabilize to the traditional teaching and learning mode. I've been using for decades now. It's going to take more than a few weeks or month to stabilize around the new one. I do think that when the dust has settled. There's a high chance we will discover taylor made and sharpened and refined set of learning and teaching mode online and a massive open online is one of these potent ial outcomes. So, I would like to thank you for participating in this experiment. we are going to continue experimenting. when I'm recording this right now, it is the end of 2012 but in 2013, when we'll roll out the spring semester, which is almost identical version as this one with things such as Grand Challenge Homework, virtual office hours on top of the quiz, the VD, the discussion forums, and homeworks. And then, in Summer 2013, we will experiment not just the format and the pedagogical engagement approaches, but also a new set of content. we have heard from many of you that the mathematical part is somewhat challenging and that is indeed the case. After all, this is a course that we designed at the beginning thinking about those students at Princeton who have taken multivariable calculus and linear algebra are ready. And we did not want to water it down or dilute it in this round but there is room to have a new course created or sister course created which would have been to call a networks illustrated. We're going to use pictures, graphs, and words with almost no equation at all except maybe adding 2 and 3 equals 5 kind of math. Nothing beyond that to explain these 20 concepts, to answer these 20 questions about technological, social, and economic networks. And that new course is in planning stage and we hope we will be able to deliver that in summer 2013. So if you would like to take this version, which is the mathematical version again, then it will be spring , 2013. This lecture might be played back towards the end of spring 2013 anyway. And, if you would like to take a new version that is independent of mathematical languages, but still go through the set of powerful concepts, ideas, and applications, then it would be summer, 2013, also on the mass multi-online platforms. And all the videos will remain on YouTube forever but in a weeks time, I think this set of content will be pulled down, but it's coming back up February the 4th 2013, and this will be likely late May or early June. It's been fun and until then have a wonderful New Year and I'll talk to you again in one of these periods. Take care and thanks.