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: 
liealgebras× 703
algebraic structures which were introduced to study the concept of infinitesimal transformations. The term "Lie algebra" (after Sophus Lie) was introduced by Hermann Weyl in the 1930s…

algebraicgroups× 703  finitegroups× 700 
riemanniangeometry× 685
a subfield of Differential Geometry, which specifically studies "Riemannian Manifolds", manifolds with "Riemannian Metrics", which means that they are equipped with continuous i…

ho.historyoverview× 669
Biographies, philosophy of mathematics, mathematics education, recreational mathematics, communication of mathematics

algorithms× 651 
primenumbers× 619
Questions where prime numbers play a keyrole, such as: questions on the distribution of prime numbers (twin primes, gaps between primes, Hardy–Littlewood conjectures, etc); questions on prime numbers…

arithmeticgeometry× 615 
stochasticprocesses× 606
a collection of random variables usually indexed by a totally ordered set.

geometry× 604
Deprecated; please use a more specific tag.

na.numericalanalysis× 594
Numerical algorithms for problems in analysis and algebra, scientific computation

computationalcomplexity× 588
computational complexity theory; complexity classes, such as P, NP, PSPACE, and so on; resourcelimited computation; NPcompleteness and other completeness concepts; oracle analogues of complexity cla…

sg.symplecticgeometry× 568
Hamiltonian systems, symplectic flows, classical integrable systems

differentialequations× 564
Ordinary or partial differential equations. Delay differential equations, neutral equations, integrodifferential equations. Wellposedness, asymptotic behavior, and related questions.

ellipticcurves× 557
an algebraic curve of genus one with some additional properties. Questions with this tag will often have the toplevel tags nt.numbertheory or ag.algebraicgeometry in addition; …

fourieranalysis× 509 
algebraicnumbertheory× 506 
differentialtopology× 501
The study of differentiable manifolds and differentiable maps. One fundamental problem is that of classifying manifolds up to diffeomorphism. Differential topology is what Poincaré understood as topol…

modularforms× 493
Questions about modular forms and related areas

analyticnumbertheory× 491
A beautiful blending of real/complex analysis with number theory. The study involves distribution of prime numbers and other problems and helps giving asymptotic estimates to these.

biglist× 479
Questions designed to generate a "big list" of certain results, examples, conjectures, etc. via many individual answers, each contributing one or a few instances. Such a question should typically be i…

cohomology× 467 
oc.optimizationcontrol× 436
Operations research, linear programming, control theory, systems theory, optimal control, game theory

banachspaces× 435
a complete normed vector space: A vector space equipped with a norm such that every Cauchy sequence converges.

tagremoved× 431
to be used only when retagging highly(!) offtopic questions where none of the actual tags would make sense; all actual tags the questioner has used are removed and something is needed to…

modeltheory× 424
the branch of mathematical logic which deals with the connection between a formal language and its interpretations, or models.

qa.quantumalgebra× 408
Quantum groups, skein theories, operadic and diagrammatic algebra, quantum field theory

complexanalysis× 395 
algebraiccurves× 388  probabilitydistributions× 383 
knottheory× 381
dealing with embedding of curves in manifolds of dimension 3. A knot is a single circle embedded in the affine space of dimension 3 as a smooth curve not crossing itself. Many knot inva…

highercategorytheory× 361 
modulispaces× 359
Given a concrete category C, with objects denoted Obj(C), and an equivalence relation ~ on Obj(C) given by morphisms in C. The moduli set for Obj(C) is the set of equivalence classes with respect to …

computabilitytheory× 355
computable sets and functions, Turing degrees, c.e. degrees, models of computability, primitive recursion, oracle computation, models of computability, decision problems, undecidability, Turing jump, …

kt.ktheoryhomology× 348
Algebraic and topological Ktheory, relations with topology, commutative algebra, and operator algebras

harmonicanalysis× 345 