[igravious]

I remember seeing many years ago a fairly dense one page diagram of how most of the major "bits" of mathematic hang together. I can never for the life of me dig it up again. Anyone know what I'm on about / got any pointers?

[Bakkot]

This may have been what you're thinking of. Sadly I lack a source; it's just been kicking around my miscellaneous images folder.

http://i.imgur.com/tBgQkxi.jpg

[friendcomputer]

That's from http://arxiv.org/pdf/gr-qc/9704009.pdf

There's some more from the author here: http://space.mit.edu/home/tegmark/crazy.html

[GuiA]

Thank you! I love the internet :)

[pohl]

So where would categories hang on that graph? Below semigroups?

[igravious]

That's it! Thanks!

[btilly]

Another good resource is http://www.math.niu.edu/~rusin/known-math/index/tour_div.htm....

[Someone]

…which is reachable from the more memorable http://www.math-atlas.org/

[jonjacky]

There is one in the book, Mathematics: Form and Function by Saunders Mac Lane (who was one of the creators of category theory).