18XX 


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} 

18Cxx 

Categories and theories 


18C05 
Equational categories [See also 03C05, 08C05] 


18C10 
Theories (e.g. algebraic theories), structure, and semantics [See also 03G30] 


18C15 
Triples (= standard construction, monad or triad), algebras for a triple, homology and derived functors for triples [See also 18Gxx] 


18C20 
Algebras and Kleisli categories associated with monads 


18C30 
Sketches and generalizations 


18C35 
Accessible and locally presentable categories 


18C50 
Categorical semantics of formal languages [See also 68Q55, 68Q65] 


18C99 
None of the above, but in this section 