Search and Browse the MSC 2000
18-XX
Category theory; homological algebra {For commutative rings see 13Dxx, for associative rings 16Exx, for groups 20Jxx, for topological groups and related structures 57Txx; see also 55Nxx and 55Uxx for algebraic topology} → ZMATH
18B10
Category of relations, additive relations → ZMATH
18B40
Groupoids, semigroupoids, semigroups, groups (viewed as categories) [See also 20Axx, 20L05, 20Mxx] → ZMATH
18B99
None of the above, but in this section → ZMATH