ASSet in nLab

category theory

• category

• functor

• natural transformation

• Cat

• universal construction

  • representable functor

  • adjoint functor

  • limit/colimit

  • weighted limit

  • end/coend

  • Kan extension

• Yoneda lemma

• Isbell duality

• Grothendieck construction

• adjoint functor theorem

• monadicity theorem

• adjoint lifting theorem

• Tannaka duality

• Gabriel-Ulmer duality

• small object argument

• Freyd-Mitchell embedding theorem

• relation between type theory and category theory

• sheaf and topos theory

• enriched category theory

• higher category theory

• applications of (higher) category theory

homotopy theory, (∞,1)-category theory, homotopy type theory

flavors: stable, equivariant, rational, p-adic, proper, geometric, cohesive, directed…

models: topological, simplicial, localic, …

see also algebraic topology

Introductions

• Introduction to Basic Homotopy Theory

• Introduction to Abstract Homotopy Theory

• geometry of physics – homotopy types

Definitions

• homotopy, higher homotopy

• homotopy type

• Pi-algebra, spherical object and Pi(A)-algebra

• homotopy coherent category theory

  • homotopical category

    • model category

    • category of fibrant objects, cofibration category

    • Waldhausen category

  • homotopy category

    • Ho(Top)

• (∞,1)-category

  • homotopy category of an (∞,1)-category

Paths and cylinders

• left homotopy

  • cylinder object

  • mapping cone

• right homotopy

  • path object

  • mapping cocone

  • universal bundle

• interval object

  • homotopy localization

  • infinitesimal interval object

Homotopy groups

• homotopy group

  • fundamental group

    • fundamental group of a topos

  • Brown-Grossman homotopy group

  • categorical homotopy groups in an (∞,1)-topos

  • geometric homotopy groups in an (∞,1)-topos

• fundamental ∞-groupoid

  • fundamental groupoid

    • path groupoid

  • fundamental ∞-groupoid in a locally ∞-connected (∞,1)-topos

  • fundamental ∞-groupoid of a locally ∞-connected (∞,1)-topos

• fundamental (∞,1)-category

  • fundamental category

Basic facts

• fundamental group of the circle is the integers

Theorems

• fundamental theorem of covering spaces

• Freudenthal suspension theorem

• Blakers-Massey theorem

• higher homotopy van Kampen theorem

• nerve theorem

• Whitehead's theorem

• Hurewicz theorem

• Galois theory

• homotopy hypothesis-theorem