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: 
kt.ktheoryhomology× 358
Algebraic and topological Ktheory, relations with topology, commutative algebra, and operator algebras

sequencesandseries× 357 
forcing× 343
a method first used to prove the continuum hypothesis is independent of the classical axioms of set theory

vectorbundles× 343
A continuously varying family of vector spaces of the same dimension over a topological space. If the vector spaces are onedimensional, the term line bundle is used and has the associated tag linebu…

inequalities× 339 
abelianvarieties× 338
projective algebraic varieties endowed with an Abelian group structure. Over the complex numbers, they can be described as quotients of a vector space by a lattice of full rank. …

computerscience× 330
For question borderline with, or having application to, computer science. Consider also posting http://cs.stackexchange.com/ or http://cstheory.stackexchange.com/ instead of here, if appropriate.

convexpolytopes× 326
the convex hulls of a finite set of points in Euclidean spaces. They have rich combinatorial, arithmetic, and metrical theory, and are related to toric varieties and to linear pr…

sheaftheory× 323 
openproblem× 319
equivalent to a known open problem, then the openproblem tag is added. After that, the question essentially becomes, "What is known about this problem? What are some…

ergodictheory× 318
Dynamical systems on measure spaces, invariant measures, ergodic averages, mixing properties.

hyperbolicgeometry× 313 
sp.spectraltheory× 312
Schrodinger operators, operators on manifolds, general differential operators, numerical studies, integral operators, discrete models, resonances, nonselfadjoint operators, random operators/matrices…

simplicialstuff× 312  examples× 311 
lattices× 307
used in number theory. (Not to be confused with lattice theory or lattices as used in physics!)

galoistheory× 298  terminology× 294  groupcohomology× 291  integration× 287 
riemannsurfaces× 272  convexity× 272 
specialfunctions× 269
Many special functions appear as solutions of differential equations or integrals of elementary functions. Most special functions have relationships with representation theory of Lie groups.

convexgeometry× 259 
diophantineequations× 259 
geometricgrouptheory× 258
Large scale properties of groups; growth functions; Dehn functions; small cancellation properties; hyperbolicity and CAT(0); actions and representations; combinatorial group theory; presentations

modelcategories× 253 
it.informationtheory× 252
Covers theoretical and experimental aspects of information theory and coding.

deformationtheory× 249  automorphicforms× 249  etalecohomology× 241 
stochasticcalculus× 241
Stochastic calculus provides a consistent theory of integration for stochastic processes and is used to model random systems. Its applications range from statistical physics to quantitative finance.

cstaralgebras× 239
a complex Banach algebra together with an isometric antilinear involution satisfying (a b)* = b* a* and the C*identity ‖a* a‖ = ‖a‖². Related tags: [tag:banachalgebras], [tag:vonne…

stacks× 237  galoisrepresentations× 233  axiomofchoice× 232 