A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
Type to find tags: 
galoisrepresentations× 240  sobolevspaces× 240 
schemes× 239
the geometrical study of solutions of algebraic systems of equations, not only over the real/complex numbers, but also over integer numbers (and more generally o…

ordertheory× 239 
bigpicture× 239
Questions designed to get an overview of a specific subject or body of results or to understand the relations among similar definitions, techniques or concepts appearing in different subfields of mat…

finitefields× 237  asymptotics× 234  topologicalgroups× 234 
fields× 233
Fields as algebraic objects. For vector and tensor fields, use eg. [dg.differentialgeometry]. For physical fields, use eg. [mp.mathematicalphysics] or [quantumfieldtheory].

operatortheory× 231
Spectrum, resolvent, numerical range, functional calculus, operator semigroups. Special classes of operators: compact, Fredholm, dissipative, differential, integral, pseudodifferential, etc.

singularitytheory× 229  3manifolds× 225 
abstractalgebra× 222 
ellipticpde× 222
Questions about partial differential equations of elliptic type. Often used in combination with the toplevel tag ap.analysisofpdes.

randommatrices× 222
Statistics of spectral properties of matrixvalued random variables.

derivedcategory× 221
For questions about the derived categories of various abelian categories and questions regarding the derived category construction itself.

noncommutativegeometry× 219
Noncommutative geometry in the sense of Connes and beyond: noncommutative algebras viewed as functions on a noncommutative space.

quadraticforms× 218 
quantumgroups× 214
Questions about algebraic structures known as quantum groups, and their categories of representations. Quasitriangular Hopf algebras and their Drinfel'd twists, triangular Hopf algebras, $C^\star$ qua…

modules× 214 
noncommutativealgebra× 213 
mathematicseducation× 212
For questions in Mathematics Education as a scientific discipline. For more handson questions on teaching Mathematics, please use the tag teaching. There is also a Stack Exchange community http://mat…

topostheory× 210  vonneumannalgebras× 210 
intuition× 208
Questions asking for the intuition behind some definition, conjecture, proof etc. In other words, questions designed to improve or to acquire understanding on a conceptual or intuitive level, as oppos…

linearprogramming× 207 
additivecombinatorics× 207
Questions on the subject additive combinatorics, also known as arithmetic combinatorics, such as questions on: additive bases, sum sets, inverse sum set theorems, sets with small doubling, Sidon sets,…

hopfalgebras× 205
a vector space $H$ over a field $k$ endowed with an associative product $\times:H\otimes_k H\to H$ and a coassociative coproduct $\Delta:H\to H\otimes_k H$ which is a morphism of alg…

descriptivesettheory× 203
the study of definable subsets of Polish spaces, where definable is taken to mean from the Borel or projective hierarchies. Other topics include infinite games and determinac…

projectivegeometry× 201  algebraicktheory× 200  commutativerings× 200 
matrixanalysis× 198
The study of the properties of real and complex matrices that are more close to analysis and operator theory. For instance: the properties of positive definite matrices, matrix inequalities, perturbat…

combinatorialgeometry× 196  approximationtheory× 188 
computationalgeometry× 186
Using computers to solve geometric problems. Questions with this tag should typically have at least one other tag indicating what sort of geometry is involved, such as ag.algebraicgeometry or mg.metr…
