Tags
A tag is a keyword or label that categorizes your question with other, similar questions.
In the ZF set theory ordinals are transitive sets which are well-ordered by $\in$. They are canonical representatives for well-orderings under order-isomorphism. In addition to the intriguing ordinal arithmetics, ordinals give a sturdy backbone to models of ZF and operate as a direct extension of the positive integers for *transfinite* inductions.
1959 questions
For questions concerning the definition and properties of limit superior and limit inferior of sequences of sets or real numbers.
1947 questions
This tag concerns computational problems central to mathematical and scientific computing. The scope includes algorithms, numerical analysis, optimization, and linear algebra, computational topology, computational geometry, symbolic methods, and inverse problems.
1945 questions
Questions about parameter estimation. Estimation theory is a branch of statistics that deals with estimating the values of parameters based on measured/empirical data that has a random component. (Def: http://en.m.wikipedia.org/wiki/Estimation_theory)
1939 questions
Fixed-point theorem is a result about existence of fixed points, i.e. points fulfilling $F(x)=x$, under some conditions on the function $F$.
Results of this type appear in many areas of mathematics, e.g. functional analysis (Banach), algebraic topology (Brouwer), lattice theory (Knaster-Tarski, Kleene) etc.
1933 questions
Plane geometry is a subfield of Euclidean geometry, restricted to the flat two-dimensional space. Plane geometry studies shapes, ratios and relative locations of 2D figures which can be embedded in a 2D plane.
1925 questions
Questions on hyperbolic geometry, the geometry on manifolds with negative curvature. For questions on hyperbolas in planar geometry, use the tag conic-sections.
1921 questions
For questions about the evaluation of finite products, or their properties. For infinite ones, use "infinite-products" tag.
1918 questions
Quotient space is a space where the underlying space is set of equivalence classes of some equivalence relation. As this concept appears in various areas, include also a tag specifying subject matter, such as (topology), (vector-spaces), (normed-spaces), etc.
1916 questions
Questions on the mathematics behind cryptography, cryptanalysis, encryption and decryption, and the making and breaking of codes and ciphers.
1915 questions
In differential geometry, the term curvature tensor may refer to the Riemann curvature tensor of a Riemannian manifold, the curvature of an affine connection or covariant derivative (on tensors), or the curvature form of an Ehresmann connection. (Def: http://en.m.wikipedia.org/wiki/Curvature_tensor)
1913 questions
For questions about prime ideals and maximal ideals in rings.
1890 questions
Questions relating to (pseudo)randomness, random oracles, and stochastic processes.
1860 questions
A symmetric matrix is a square matrix that is equal to its transpose.
1854 questions
Questions about (linear or nonlinear) least-squares, an estimation method used in statistics, signal processing and elsewhere.
1853 questions
Automata Theory, including abstract machines, grammars, parsing, grammatical inference, transducers, and finite-state techniques
1841 questions
This tag is for questions about finding a Laurent series of functions and their convergence. The Laurent series is a generalisation of the power series which allows negative indices and is essential for investigating the behaviour of functions near poles.
1827 questions
The quantifiers $\forall$ ("for all") and $\exists$ ("there exists") distinguish predicate calculus from propositional logic.
1826 questions
For question involving functions satisfying a Lipschitz continuity condition, that is, the distance ratio about the distance of $f(x)$ and $f(y)$ and that of $x$ and $y$ can be bounded independently of $x$ and $y$.
1807 questions
Use this tag for questions about source-coding and channel-coding in information theory, error-correcting codes, error-detecting codes, and related algebraic and/or combinatoric constructions. This tag should not be used for questions about programming.
1802 questions
For questions about Sylow theorems in the context of group theory. Not for use with questions regarding Sylow systems, which belong in solvable-groups.
1795 questions
For questions on axioms, mathematical statements that are accepted as being true, usually without controversy.
1787 questions
For questions concerning the properties and solutions to the boundary-value problem for differential equations. By a Boundary value problem, we mean a system of differential equations with solution and derivative values specified at more than one point. Most commonly, the solution and derivatives are specified at just two points (the boundaries) defining a two-point boundary value problem.
1754 questions
The study of vector space with a topology which makes the maps which sums two vectors and which multiply a vector by a scalar continuous. It's a natural generalization of normed spaces.
1748 questions
For questions about positive definite real or complex matrices. For questions about positive semi-definite matrices, use the (positive-semidefinite) tag.
1742 questions
For questions regarding computation and results related to integrals in at least 2 variables.
1740 questions
For questions about or involving fundamental groups of topological spaces, as well as related topics such as fundamental groupoids and étale fundamental groups.
1726 questions
For questions about trace, which can concern matrices, operators or functions.
If your question concerns the trace map that maps a Sobolev function to its boundary values, please use [trace-map] instead.
1724 questions
For questions about congruences in modular arithmetic, concerning for example the chinese remainder theorem, Fermat's little theorem or Euler's totient theorem.
1724 questions
Questions on whether certain series diverge, and how to deal with divergent series using summation methods such as Ramanujan summation and others.
1714 questions
Questions related with (base 2) representation of numbers and their unique properties arising out of number representation.
1703 questions
For questions on quantum mechanics, a branch of physics dealing with physical phenomena at microscopic scales.
1699 questions
For questions about or involving covering spaces in algebraic topology.
1696 questions