Topos Category Theory by Example
Topos theory studies categories that behave like generalized universes of sets.
Archive
February 2019
Yoneda's Lemma Category Theory by Example
Yoneda's lemma explains how an object of a locally small category is determined by the morphisms into or out of it.
Natural Transformations Category Theory by Example
Natural transformations compare functors component by component and organize functors into their own categories.
Functors Category Theory by Example
Functors map objects and morphisms between categories while preserving composition and identity.