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.
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mathematicseducation× 221
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…

motives× 218
In algebraic geometry, a motive (or sometimes motif, following French usage) denotes 'some essential part of an algebraic variety'. One has a satisfactory description of pure motives, whereas the mixe…

stablehomotopy× 215
that part of homotopy theory (and thus algebraic topology) concerned with all structure and phenomena that remain after sufficiently many applications of the suspension funct…

hodgetheory× 214
The study of harmonic differential forms on complex projective varieties, their invariantly defined filtrations, their integrals over topological cycles, especially over subvarieties, the deformations…

randomwalk× 214 
birationalgeometry× 214
a field of algebraic geometry the goal of which is to determine when two algebraic varieties are isomorphic outside lowerdimensional subsets. This amounts to studying mappings …

computationalgeometry× 214
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…

limitsandconvergence× 213
Convergence of series, sequences and functions and different modes of convergence.

algebraicsurfaces× 212
an algebraic variety of dimension two. In the case of geometry over the field of complex numbers, an algebraic surface has complex dimension two (as a complex manifold, when it…

eigenvalues× 211 
euclideangeometry× 207
a mathematical system attributed to the Alexandrian Greek mathematician Euclid, which he described in his textbook on geometry: the Elements. Euclid's method consists in assuming…

manifolds× 204
a topological space that locally resembles Euclidean space near each point. More precisely, each point of an ndimensional manifold has a neighbourhood that is homeomorphic to the Euclid…

mathphilosophy× 202
Philosophical aspects of logic and set theory; truth status of mathematical axioms; Philosophy of Mathematics; philosophical aspects of mathematics in general; relation of mathematics to philosophy; e…

riemannzetafunction× 202
the function of one complex variable $s$ defined by the series $\zeta(s) = \sum_{n \geq 1} \frac{1}{n^s}$ when $\operatorname{Re}(s)>1$. It admits a meromorphic continuati…

differentialoperators× 198
Elliptic, parabolic and hyperbolic operators. Laplace, LaplaceBeltrami, Schrödinger, Dirac. Exterior derivative and Lie derivative operators.

teaching× 196
For questions related to teaching mathematics. For questions in Mathematics Education as a scientific discipline there is also the tag mathematicseducation. Note you may also ask your question on htt…

monoidalcategories× 195 
graphcolorings× 194
Vertex colouring, Edge Colouring, List Colouring, Fractional Chromatic Number and other variants of graph colouring problems are all on topic.

textbookrecommendation× 194
Questions asking for recommendations of textbooks on some subject. It can be helpful to indicate whether the request is for selfstudy, for use in a course one teaches, for use accompanying a course o…

groupactions× 192 
characteristicp× 191 
combinatorialgeometry× 190

calculusofvariations× 188 
geometricmeasuretheory× 186
Questions about geometric properties of sets using measure theoretic techniques; rectifiability of sets and measures, currents, Plateau problem, isoperimetric inequality and related topics.

kahlermanifolds× 186
Questions about Kähler manifolds and Kähler metrics.

lfunctions× 182
Questions about generalizations of the Riemann Zeta function of arithmetic interest whose definition relies on meromorphic continuation of special kinds of Dirichlet series, such as Dirichlet Lfuncti…

semigroups× 181
a set $S$ together with a binary operation that is associative. Examples of semigroups are the set of finite strings over a fixed alphabet (under concatenation) and the positive intege…

permutations× 181
Questions related to permutations, bijections from a finite (or sometimes infinite) set to itself.

prooftheory× 178
For question in Proof Theory, where "proofs" themselves are the object of mathematical investigation. It is not to be used to request a proof of some result.

spectralgraphtheory× 178
Questions related to the spectrum of graphs, defined using one of the possible variants of the discrete Laplace operator or Laplacian matrix.
See https://en.wikipedia.org/wiki/Discrete_Laplace_oper…

planegeometry× 176 
nonlinearoptimization× 175
Nonlinear objectives, nonlinear constraints, nonconvex objective, nonconvex feasible region.

invarianttheory× 174
Invariant theory deals with an algebraic, geometric or analytic structure X , submited to the action of an (algebraic) group G . It studies Ginvariant elements of X as well as the set of Gorbits.

computeralgebra× 174
Using computers to solve algebraic problems. Questions with this tag should typically include at least one other tag indicating what sort of algebraic problem is involved, such as ac.commutativealgeb…

classfieldtheory× 173 
symmetricgroup× 171
the group of permutations of the set of integers $\{1,\dots,n\}$. This has $n!$ elements and is generated by the $n1$ involutions exchanging consecutive integers. The sym…
