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I've been reading "MacLane's Categories for the Working Mathematician" today because I was trying to find out how the proof of the Coherence Theorem for strict monoidal categories goes, and holy crap is there a lot of stuff in that book that makes so much more sense now. Freakin'

This is a nice page full of HTML entities for math symbols: http://en.wikipedia.org/wiki/Mathematical_HTML

**everything**is a monoid object in a suitable monoidal category. Categories themselves? Monoid objects in <**O-Graph**, ×_{O}, id>. Monads? Monoid objects in <**C**, ∘, id>. Rings? Monoid objects in <^{C}**Ab**, ⊗,**Z**>. And if it's not a monoid object, it's the action of one. Modules are actions of rings, suitable group actions are torsors, monad actions are T-algebras, which themselves include the remainder of the usual zoo of algebraic structures like semigroups, groups, etc.This is a nice page full of HTML entities for math symbols: http://en.wikipedia.org/wiki/Mathematical_HTML