## Mathematics Subject Classification – MSC2010

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

Instructional exposition (textbooks, tutorial papers, etc.) 520

Research exposition (monographs, survey articles) 617

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

Topological spaces and generalizations (closure spaces, etc.) 3187

Several topologies on one set (change of topology, comparison of topologies, lattices of topologies) 1580

Convergence in general topology (sequences, filters, limits, convergence spaces, etc.) 2411

Cardinality properties (cardinal functions and inequalities, discrete subsets) [See also 03Exx] [For ultrafilters, see 54D80] 2590

Special maps on topological spaces (open, closed, perfect, etc.) 4066

Absolute neighborhood extensor, absolute extensor, absolute neighborhood retract (ANR), absolute retract spaces (general properties) [See also 55M15] 1185

Connected and locally connected spaces (general aspects) 1486

Lower separation axioms ($T_0$--$T_3$, etc.) 2156

Higher separation axioms (completely regular, normal, perfectly or collectionwise normal, etc.) 1928

Noncompact covering properties (paracompact, Lindelöf, etc.) 3713

Extensions of spaces (compactifications, supercompactifications, completions, etc.) 2847

Special constructions of spaces (spaces of ultrafilters, etc.) 430

Descriptive set theory (topological aspects of Borel, analytic, projective, etc. sets) [See also 03E15, 26A21, 28A05] 1532