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× 234  axiomofchoice× 234 
bigpicture× 233
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…

asymptotics× 231 
ordertheory× 227  singularitytheory× 226  finitefields× 226  topologicalgroups× 226 
fields× 221
Fields as algebraic objects. For vector and tensor fields, use eg. [dg.differentialgeometry]. For physical fields, use eg. [mp.mathematicalphysics] or [quantumfieldtheory].

3manifolds× 221 
randommatrices× 218
Statistics of spectral properties of matrixvalued random variables.

abstractalgebra× 216 
noncommutativegeometry× 215
Noncommutative geometry in the sense of Connes and beyond: noncommutative algebras viewed as functions on a noncommutative space.

sobolevspaces× 214  quadraticforms× 212  noncommutativealgebra× 210 
derivedcategory× 210
For questions about the derived categories of various abelian categories and questions regarding the derived category construction itself.

mathematicseducation× 209
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…

quantumgroups× 209
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…

topostheory× 208 
linearprogramming× 206  modules× 206 
ellipticpde× 206
Questions about partial differential equations of elliptic type. Often used in combination with the toplevel tag ap.analysisofpdes.

intuition× 205
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…

vonneumannalgebras× 204 
operatortheory× 202
Spectrum, resolvent, numerical range, functional calculus, operator semigroups. Special classes of operators: compact, Fredholm, dissipative, differential, integral, pseudodifferential, etc.

hopfalgebras× 199
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…

combinatorialgeometry× 196 
additivecombinatorics× 195
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,…

algebraicktheory× 193  commutativerings× 189  descriptivesettheory× 189 
matrixanalysis× 189
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…

markovchains× 186  projectivegeometry× 186  motives× 183 