
A concise introduction to category theory - lisper
http://ncatlab.org/nlab/show/category+theory
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ericssmith
If you want an actual introduction to the topic, "Conceptual Mathematics: A
First Introduction to Categories" by Lawvere and Schanuel is the right choice.

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agumonkey
Funny coincidence, I just found this video
[http://www.reddit.com/r/haskell/comments/1l4ph3/dsls_and_tow...](http://www.reddit.com/r/haskell/comments/1l4ph3/dsls_and_towers_of_abstraction_with_gershom/)
back, where the speaker mentions many CT ideas (adjoint functors, galois
connections) and end up pointing at abstract interpretation and Lawvere work.

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ikeboy
This seems to be down right now
[https://archive.today/vibrM](https://archive.today/vibrM) , however it's
still available in google cache here
[https://webcache.googleusercontent.com/search?q=cache:PKJbiW...](https://webcache.googleusercontent.com/search?q=cache:PKJbiWKTpScJ:ncatlab.org/nlab/show/category%2Btheory+&cd=1&hl=en&ct=clnk&gl=us)
. Anyone know what's up?

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OscarCunningham
nLab is often slow. It can't cope with its normal amount of traffic, so
certainally not with front page HN.

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anonymouz
Sure, it's concise, but I'd hardly describe ncatlab as introduction. It's more
of a reference. I'd dare say the Wikipedia entry on category theory (and
related links) makes a better introduction for the uninitiated.

To actually learn it, Mac Lane & Saunders "Categories for the Working
Mathematician." seems to enjoy continued popularity.

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nbouscal
MacLane is still the standard for working mathematicians, but for those with
less background, Steve Awodey's book[1] is very good. He also has some YouTube
lectures[2]. While you're on YouTube, the Catsters channel[3] has many
excellent 10-minute category theory videos.

[1] [http://www.amazon.com/Category-Theory-Oxford-Logic-
Guides/dp...](http://www.amazon.com/Category-Theory-Oxford-Logic-
Guides/dp/0199237182)

[2][https://www.youtube.com/playlist?list=PLGCr8P_YncjVjwAxrifKg...](https://www.youtube.com/playlist?list=PLGCr8P_YncjVjwAxrifKgcQYtbZ3zuPlb)

[3][https://www.youtube.com/channel/UC5Y9H2KDRHZZTWZJtlH4VbA](https://www.youtube.com/channel/UC5Y9H2KDRHZZTWZJtlH4VbA)

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Verdex
I can second the Catsters channel. As a complete category theory newbie
watching those videos was nevertheless enjoyable because of the upbeat and
cheerful attitude with which the material was covered.

I actually found MacLane's book to be more approachable than Awodey's.
Although I'm not sure this is good advice because it took me several years
casually feeling my way through the field to start to gain an understanding
into it (ie YMMV).

Interesting category theory historical fact! Checkout MacLane's wikipedia page
and you will find one of his students was in fact Steve Awodey.

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antimora
Tom LaGatta in this video on Category Theory listed this website as number one
resource on category theory.

[http://youtu.be/o6L6XeNdd_k?t=1h5m31s](http://youtu.be/o6L6XeNdd_k?t=1h5m31s)

There he also lists some books on category theory. I am putting a direct link
when he mentions the references.

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sago
Should we read this page as suggesting a prerequisite to learning category
theory is being able to interpret LaTeX math mode on the fly?

Or did a bit of javascript magic not load for me?

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lisper
Something is wrong on your end, but it's not Javascript. It looks fine to me
both with and without JS.

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sago
/Snark Thanks, tried it again and the images loaded. Must have been the alt-
tags I was seeing. Much obliged.

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lisper
Actually, they're not images. They're MathML markup.

[http://www.w3.org/Math/](http://www.w3.org/Math/)

