## Mathematics Subject Classification – MSC2010

General reference works (handbooks, dictionaries, bibliographies, etc.) 26

Instructional exposition (textbooks, tutorial papers, etc.) 518

Research exposition (monographs, survey articles) 613

Explicit machine computation and programs (not the theory of computation or programming) 18

Topological spaces and generalizations (closure spaces, etc.) 3159

Several topologies on one set (change of topology, comparison of topologies, lattices of topologies) 1567

Convergence in general topology (sequences, filters, limits, convergence spaces, etc.) 2390

Cardinality properties (cardinal functions and inequalities, discrete subsets) [See also 03Exx] [For ultrafilters, see 54D80] 2577

Special maps on topological spaces (open, closed, perfect, etc.) 4046

Absolute neighborhood extensor, absolute extensor, absolute neighborhood retract (ANR), absolute retract spaces (general properties) [See also 55M15] 1183

Connected and locally connected spaces (general aspects) 1472

Lower separation axioms ($T_0$--$T_3$, etc.) 2131

Higher separation axioms (completely regular, normal, perfectly or collectionwise normal, etc.) 1912

Noncompact covering properties (paracompact, Lindelöf, etc.) 3698

Extensions of spaces (compactifications, supercompactifications, completions, etc.) 2834

Special constructions of spaces (spaces of ultrafilters, etc.) 422

Descriptive set theory (topological aspects of Borel, analytic, projective, etc. sets) [See also 03E15, 26A21, 28A05] 1518