## Mathematics Subject Classification – MSC2010

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

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

Research exposition (monographs, survey articles) 615

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

Topological spaces and generalizations (closure spaces, etc.) 3172

Several topologies on one set (change of topology, comparison of topologies, lattices of topologies) 1571

Convergence in general topology (sequences, filters, limits, convergence spaces, etc.) 2392

Cardinality properties (cardinal functions and inequalities, discrete subsets) [See also 03Exx] [For ultrafilters, see 54D80] 2581

Special maps on topological spaces (open, closed, perfect, etc.) 4049

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) 1475

Lower separation axioms ($T_0$--$T_3$, etc.) 2140

Higher separation axioms (completely regular, normal, perfectly or collectionwise normal, etc.) 1917

Noncompact covering properties (paracompact, Lindelöf, etc.) 3706

Extensions of spaces (compactifications, supercompactifications, completions, etc.) 2840

Special constructions of spaces (spaces of ultrafilters, etc.) 427

Descriptive set theory (topological aspects of Borel, analytic, projective, etc. sets) [See also 03E15, 26A21, 28A05] 1521