Homotopy theory Algebraic topology 9 Categories (Mathematics) 5 Geometry, Algebraic 5 Algebra, Homological 4 Loop spaces 4 Homology theory 3 more ... Low-dimensional topology 3 Mathematics 3 Representations of groups 3 Topology 3 C*-algebras 2 CW complexes 2 Combinatorial group theory 2 Combinatorial topology 2 Commutative algebra 2 Differential forms 2 Four-manifolds (Topology) 2 Group theory 2 Homotopy groups 2 K-theory 2 Manifolds (Mathematics) 2 Rational points (Geometry) 2 Rings (Algebra) 2 Schemes (Algebraic geometry) 2 Torsion theory (Algebra) 2 Associative rings 1 Calculus 1 Cauchy-Riemann equations 1 Cobordism theory 1 less ...