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# Welcome to the Applied Category Theory Course!

edited October 2018

Hi! Welcome to the Applied Category Theory Course. I'm no longer giving lectures, but the resources are still available and you can still discuss the course here!

A good first step is to download a copy of the text:

The most important thing is to read and discuss my Lectures and try to do the Exercises.

On Monday May 7th we'll start Chapter 2. There's also place for discussing Chapter 1 if you want to catch up.

This course will only be fun if you actively participate. You have to ask questions, answer puzzles, and do exercises from the book, to make progress. If you can answer other students' questions, do so. There are a lot of other smart people around to talk to! Go to Chat and meet some!

If you think you've found a mistake in the book, please report it here:

If it's really a mistake, Fong and Spivak will fix it!

Getting to Know Each Other

Chat is a good place for more free-wheeling discussions. I think we're gonna have tons of fun. Some of us will wind up doing interesting projects together! I want to help save the planet, and this is one way to get started.

Writing math

You can write equations using MathJax, which is a limited version of LaTeX good for the web. For "displayed" equations, centered on the page, use double dollar signs: $$E = \sqrt{m^2 + p^2}$$ produces this: $$E = \sqrt{m^2 + p^2}$$ For "inline" equations, mixed in with your text, use this other method: \$$E = \sqrt{m^2 + p^2}\$$ produces this: $$E = \sqrt{m^2 + p^2}$$.

Questions

If you have questions or comments on the subject of the course that don't quite fit into any of the chapter discussions, you can start a new discussion in the category Applied Category Theory Course. If you have questions about how the Azimuth Forum works, start a discussion in the category Technical.

Be Nice

It's an inevitable feature of any discussion forum that some users become rude, bully others, try to take over conversations, or try to exploit the forum as a venue to promote irrelevant ideas. Anyone who becomes annoying in these or other ways will be blocked. So be polite, be friendly, and let's focus on the course material!

Let's Go!

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1.
edited March 2018

Thanks for this great course !

Comment Source:Thanks for this great course !
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2.
edited March 2018

You're welcome! If everyone asks lots of questions and answers lots of other people's questions, it will be lots of fun. There's a limit to how many minutes a day I can put into this. But we've got about 90 people here, so multiply that by 90 and it becomes a formidable engine for knowledge generation.

Comment Source:You're welcome! If everyone asks lots of questions and _answers_ lots of other people's questions, it will be lots of fun. There's a limit to how many minutes a day I can put into this. But we've got about 90 people here, so multiply that by 90 and it becomes a formidable engine for knowledge generation.
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3.

I suggest having deadlines for more-or-less (no need to be strict that I can see) finishing each chapter. John, I know you're playing this by ear (which is great IMO), but maybe you could make up the deadlines as we go along, a chapter at a time?

Comment Source:I suggest having deadlines for more-or-less (no need to be strict that I can see) finishing each chapter. John, I know you're playing this by ear (which is great IMO), but maybe you could make up the deadlines as we go along, a chapter at a time?
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4.

Comment Source:I'm voting against deadlines :)
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5.

Is it possible to be a passive student? While I love to do problems, with work and family it is going to be hard to find time but I definitely want to be engaged in the learning. Apologies for the selfishness.

Comment Source:Is it possible to be a passive student? While I love to do problems, with work and family it is going to be hard to find time but I definitely want to be engaged in the learning. Apologies for the selfishness.
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6.

Jason and Igor: I'm not going to make up deadlines to look at each chapter, but I will march ahead, giving lectures on each chapter and then moving on to the next one... and I will focus most of my attention on discussions about what I just discussed, though people are free to continuing each topic ad infinitum.

There will be a discussion thread about each chapter, and one about each lecture, and perhaps one about each exercise (or group of related exercises?)

Comment Source:Jason and Igor: I'm not going to make up deadlines to look at each chapter, but I will march ahead, giving lectures on each chapter and then moving on to the next one... and I will focus most of my attention on discussions about what I just discussed, though people are free to continuing each topic _ad infinitum_. There will be a discussion thread about each chapter, and one about each lecture, and perhaps one about each exercise (or group of related exercises?)
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7.

Sri Panyam: it's possible to be a passive student; you may have less fun than the people who engage more. Whenever you have questions or comments, please post them!

Comment Source:Sri Panyam: it's possible to be a passive student; you may have less fun than the people who engage more. Whenever you have questions or comments, please post them!
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8.
edited March 2018

@JohnBaez What should the top level discussions be? I see

• Chapter #
• Lecture # - Chapter #

You mentioned discussions on exercises, so?...

• Exercise #

I also suggest...

• Puzzle # - Chapter # :

I have completed all the exercises for chapter 1. Should I start posting them? I am also really interested in the responses for your puzzle 4 for chapter 1. It would nice if they were collected somewhere, should they be in the wiki?

Comment Source:@JohnBaez What should the top level discussions be? I see * Chapter # * Lecture # - Chapter # You mentioned discussions on exercises, so?... * Exercise # I also suggest... * Puzzle # - Chapter # : <name> I have completed all the exercises for chapter 1. Should I start posting them? I am also really interested in the responses for your puzzle 4 for chapter 1. It would nice if they were collected somewhere, should they be in the wiki?
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9.

Frederick - yes, I agree that we should have top-level discussions of the types you mention! I'd love to see some of the sort

• Exercise #

and

• Puzzle # - Chapter #

So, please start them! It would be nice if the first post in such discussions merely stated the exercise and/or puzzle. Then the next post could be your solution (or someone's solution), and then other solutions and discussion thereof. If I get ahold of the LaTeX for Seven Sketches, this may reduce the amount of typing required.

There is already a partial list of responses to puzzle 4 here:

Comment Source:Frederick - yes, I agree that we should have top-level discussions of the types you mention! I'd _love_ to see some of the sort * Exercise # and * Puzzle # - Chapter # So, please start them! It would be nice if the first post in such discussions merely stated the exercise and/or puzzle. Then the next post could be your solution (or someone's solution), and then other solutions and discussion thereof. If I get ahold of the LaTeX for _Seven Sketches_, this may reduce the amount of typing required. There is already a partial list of responses to puzzle 4 here: * [Responses to Puzzle 4](https://forum.azimuthproject.org/discussion/1822/puzzle-4-responses) Over there, [Daniel Cellucci and I are started to discuss using the Azimuth Wiki to store information like answers to puzzles](https://forum.azimuthproject.org/discussion/comment/16242/#Comment_16242). 
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10.
edited June 2018

I deleted my original comment: I proposed a different top-level naming scheme, but having visited the forum, it works out great as it is. Thank you for this inititiative!

Comment Source:I deleted my original comment: I proposed a different top-level naming scheme, but having visited the forum, it works out great as it is. Thank you for this inititiative!
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11.

Sure, Daniel!

Comment Source:Sure, Daniel!