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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matrixanalysis× 168
The study of real and complex matrices and their algebraic and analytical properties, including: eigenvalues and eigenvectors, positive definite matrices, matrix inequalities, invariant subspaces, per…

projectivegeometry× 168 
operatortheory× 164
Spectrum, resolvent, numerical range, functional calculus, operator semigroups. Special classes of operators: compact, Fredholm, dissipative, differential, integral, pseudodifferential, etc.

ellipticpde× 164
Questions about partial differential equations of elliptic type. Often used in combination with the toplevel tag ap.analysisofpdes.

stablehomotopy× 162  approximationtheory× 160  manifolds× 160  mathphilosophy× 157 
algebraicsurfaces× 157 
computationalgeometry× 157
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…

birationalgeometry× 153  hilbertspaces× 147 
computeralgebra× 145
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…

semigroups× 145  randomwalk× 145  euclideangeometry× 144 
monoidalcategories× 143 
textbookrecommendation× 143
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…

langlandsconjectures× 142
Higher reciprocity laws

riemannzetafunction× 142
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…

prooftheory× 142
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.

lfunctions× 137
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…

universalalgebra× 135  zetafunctions× 135 
homology× 134  groupactions× 134 
books× 132
Questions in which books play a keyrole, such as questions on antique books, ebooks, difference between various editions of a book, etc. For questions asking for recommendations of books on some sub…

calculusofvariations× 131 
gm.generalmathematics× 131  convexoptimization× 127  classfieldtheory× 127 
differentialoperators× 126
Elliptic, parabolic and hyperbolic operators. Laplace, LaplaceBeltrami, Schrödinger, Dirac. Exterior derivative and Lie derivative operators.

intersectiontheory× 122  career× 121  graphcolorings× 120  geometricmeasuretheory× 116 