MSC results for "18"

**18**(1940-now) 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]

**18-00**(1973-now) General reference works (handbooks, dictionaries, bibliographies, etc.)

**18-01**(1973-now) Instructional exposition (textbooks, tutorial papers, etc.)

**18-02**(1973-now) Research exposition (monographs, survey articles)

**18-03**(1973-now) Historical (must also be assigned at least one classification number from Section 01)

**18-04**(1980-now) Explicit machine computation and programs (not the theory of computation or programming)

**18-06**(1973-now) Proceedings, conferences, collections, etc.

**18A**(1973-now) General theory of categories and functors

**18B**(1973-now) Special categories

**18C**(1973-now) Categories and theories

**18D**(1973-now) Categories with structure

**18E**(1973-now) Abelian categories

**18F**(1973-now) Categories and geometry

**18H**(1973-1979) Cohomology of specified algebraic systems

**18.00**(1959-1972) General

**18.0**(1940-1958) Homological algebra

**18.15**(1959-1972) Abelian categories

**18.20**(1959-1972) Homological algebra

**18.99**(1959-1972) None of the above, but in this section