Pathway V

→Category theory

Objects and arrows. Composition, commutative squares, and Yoneda’s lemma.

1. 01Objects and arrowsA category is objects plus composable arrows, with identities. Diagrams commute when both paths agree.4 min
2. 02YonedaAn object is determined by the maps into it. Hom(−, X) is a complete fingerprint.4 min
3. 03FunctorsA functor sends objects to objects and arrows to arrows, and it preserves identities and composition.4 min