Textbook Group meeting for Parr, Pezzulo, Friston 2022 .

Okay, it is May 19th, 2022, and it's week three of the textbook group, first cohort. We're in week three, discussing Appendix A and B, and there are some notes in the sections of the book, in the chapters. There are also some ideas and questions that people have raised. So, we'll go to the questions and then start with the most upvoted, so feel free to add more upvotes if you want to discuss it, like even in this discussion. And then, hopefully, if people are available to take notes in this section, that will help add their thoughts in and also capture what the speakers are saying. And then, we'll look at the question and then try to come to different answers and just add more information that people can add more structure to later. Okay, the first question says, Appendix A is described as the mathematical background. So, maybe question one. For the authors, or for you, what is the process of determining what is figure and ground for the formalisms of active? What other math concepts and formalisms are important for learning and applying active inference? And then, three, what are some resources and approaches for learning math that help us learn what is useful for active inference? Okay. Anyone can raise their hand, or we can just start to add some annotations here. Like, what should be included in the primary regime of attention with the reading of a book, either linearly, like some books are, or in a maybe moving around the sections? So, what should be in the chapters? What should be in the appendix? What is not in the appendix? What did people expect would be in the chapter, in the appendix, not covered? Okay. Yeah, Jessica, and then anyone else? Hello. Yeah, I was wondering about the multiplication of the matrices that we covered yesterday. Which equations have the multiplication of the matrices? Like, a couple of examples, just so that I can, like, play around with them? Like, in the actual, like, active inference equations. Does anyone know one? This is referencing the way that the appendix A is starting with linear algebra, and then introducing this operation of multiplying two matrices to get a product. If someone can find, like, an equation from the, that we've already seen, or some other equation while I'm typing up that question, that would be helpful. Okay. That sounds weird. Can anyone just describe what they thought the intention was of starting with linear algebra and using 8.1 as the first equation of the appendix or we'll return to just the more general questions yeah um i mean linear algebra is kind of the most discrete um i don't want to say fundamental but like uh practical and comprehensive way of kind of working with a large space of data i guess um together and computing on it so it's kind of the basis for the discrete uh parts and maybe easier than the non-discrete parts good reason to start i guess if the question was um where is linear algebra used in the active inference and math um when you go to appendix b then you've got the equations of active inference and these are all expressed in terms of large vector spaces of variables so probability distributions and so for example on page 245 you've got this dot notation which is the expectation of a value so that right that goes directly back to that first section of appendix a is what does that mean in terms of how do you take an expectation of a large vector of things how do you express that compactly thanks uh could you unpack we looked at the dot notation a little bit in uh yesterday and they were mentioning how well i think it was actually one of the questions too let's just see if someone asks this okay they say the dot operator in a3 the dot operator is equivalent to standard matrix multiplication where the first matrix has been transposed so what is the relationship with expectation when we're talking like what are where how does expectation this is for anyone how does expectation relate to linear algebra the probability of a value so you're…