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| | week53 |
 | | An n-category is a mathematical structure containing not only objects, which one might think of as "things", and morphisms, which one might think of as "processes leading from one thing to another", but also 2-morphisms, which are "processes leading from one process to another", and then 3-morphisms, etc., on up to n-morphisms. |
 | | Moreover, we should think of Th as a category with all finite limits, that is, one in which all finite diagrams have limits. |
 | | Well, if a model is a sort of functor, a morphism between them should be a sort of natural transformation between functors; that's how it usually goes. |
| math.ucr.edu /home/baez/week53.html (2436 words) |
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