MSC results for "20"

**20**(1940-now) Group theory and generalizations

**20-00**(1973-now) General reference works (handbooks, dictionaries, bibliographies, etc.)

**20-01**(1973-now) Instructional exposition (textbooks, tutorial papers, etc.)

**20-02**(1973-now) Research exposition (monographs, survey articles)

**20-03**(1973-now) Historical (must also be assigned at least one classification number from Section 01)

**20-04**(1973-now) Explicit machine computation and programs (not the theory of computation or programming)

**20-06**(1973-now) Proceedings, conferences, collections, etc.

**20A**(1973-now) Foundations

**20B**(1973-now) Permutation groups

**20C**(1973-now) Representation theory of groups [See also 19A22 (for representation rings and Burnside rings)]

**20D**(1973-now) Abstract finite groups

**20E**(1973-now) Structure and classification of infinite or finite groups

**20F**(1973-now) Special aspects of infinite or finite groups

**20G**(1973-now) Linear algebraic groups and related topics [For arithmetic theory, see 11E57, 11H56; for geometric theory, see 14Lxx, 22Exx; for other methods in representation theory, see 15A30, 22E45, 22E46, 22E47, 22E50, 22E55]

**20J**(1973-now) Connections with homological algebra and category theory

**20K**(1973-now) Abelian groups

**20L**(1973-now) Groupoids (i.e. small categories in which all morphisms are isomorphisms) [For sets with a single binary operation, see 20N02; for topological groupoids, see 22A22, 58H05]

**20M**(1973-now) Semigroups

**20N**(1973-now) Other generalizations of groups

**20.00**(1959-1972) General

**20.08**(1959-1972) Varieties of groups

**20.0**(1940-1958) Group theory and generalizations

**20.10**(1959-1972) Group presentations; free groups, generators, relations

**20.15**(1959-1972) Periodic groups

**20.18**(1959-1972) Groups with local properties

**20.20**(1959-1972) Groups acting on sets, permutation groups

**20.22**(1959-1972) Automorphism groups

**20.25**(1959-1972) Finite group theory

**20.27**(1959-1972) Structure of groups, classification

**20.29**(1959-1972) Simple groups

**20.30**(1959-1972) Abelian groups

**20.40**(1959-1972) Nilpotent, solvable, $p$-groups

**20.43**(1959-1972) Sylow subgroups, $\Pi$-subgroups

**20.48**(1959-1972) Group extensions

**20.50**(1959-1972) Homological methods in group theory

**20.51**(1959-1972) Limits of systems of groups

**20.52**(1959-1972) General products of groups (including semidirect, wreath, free, amalgamated)

**20.54**(1959-1972) Special subgroups

**20.56**(1959-1972) Series of subgroups

**20.58**(1959-1972) Lattices of subgroups

**20.60**(1959-1972) Crystallographic and discrete geometric groups

**20.65**(1959-1972) Modular groups, discrete subgroups of classical groups

**20.72**(1959-1972) Collineation groups

**20.80**(1959-1972) Representations, characters, group algebras

**20.85**(1959-1972) Representations of symmetric groups

**20.90**(1959-1972) Semigroup algebras, representations, characters

**20.93**(1959-1972) Semigroups, structure and classification

**20.95**(1959-1972) Other binary systems; groupoids, quasigroups, loops

**20.97**(1959-1972) Ternary systems; heaps, semiheaps, heapoids

**20.99**(1959-1972) None of the above, but in this section