Category of small categories

In mathematics, specifically in category theory, the category of small categories, denoted by Cat, is the category whose objects are all small categories and whose morphisms are functors between categories. Cat may actually be regarded as a 2-category with natural transformations serving as 2-morphisms.

The category Cat is itself a large category, and therefore not an object of itself. In order to avoid problems analogous to Russell’s paradox one cannot form the “category of all categories”. But it is possible to form a quasicategory of all categories.

— Wikipedia on Category of small categories

2010.04.03 Saturday ACHK

Product

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I think the solution is to assume that anything you’ve made is far short of what it could be. Force yourself, as a sort of intellectual exercise, to keep thinking of improvements. Ok, sure, what you have is perfect. But if you had to change something, what would it be?

If your product seems finished, there are two possible explanations: (a) it is finished, or (b) you lack imagination. Experience suggests (b) is a thousand times more likely.

— Paul Graham

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2010.04.03 Saturday ACHK