Every idea

Ideas 9751–9900 of 10181.

Name	Kind	Subject
Non-atomic measure	Definition	Measure and integration
Sorgenfrey line	Counterexample	General topology
Eigenvalue perturbation	Definition	Linear and multilinear algebra; matrix theory
Associative quotient of a magma	Definition	Group theory and generalizations
Schur–Horn theorem	Theorem	Linear and multilinear algebra; matrix theory
Galerkin method	Concept	Numerical analysis
Mal'cev term	Definition	General algebraic systems
Semi-continuity	Definition	Real functions
Generic flatness	Theorem	Algebraic geometry
Completion of a topological group	Definition	Topological groups, Lie groups
Structure	Definition	Mathematical logic and foundations
Divisor class group	Definition	Commutative algebra
Injectivity radius	Concept	Differential geometry
Glimm scheme	Concept	Partial differential equations
Numerical range	Definition	Operator theory
Castelnuovo–Mumford regularity	Concept	Commutative algebra
Hurewicz fibration	Concept	Algebraic topology
Universal coalgebra	Definition	General algebraic systems
de Branges space	Definition	Functional analysis
Lagrange polynomial	Concept	Approximations and expansions
Complex torus	Concept	Algebraic geometry
Cheeger constant	Concept	Combinatorics
Exponential map	Concept	Differential geometry
Brauer–Manin obstruction	Definition	Algebraic geometry
Prime knot	Definition	Manifolds and cell complexes
Infinite compositions of functions	Definition	Sequences, series, summability
Second-order arithmetic	Definition	Mathematical logic and foundations
Hodge structure	Definition	Algebraic geometry
Continuous and residual spectrum	Definition	Operator theory
Measure with density	Concept	Measure and integration
Germ	Definition	General topology
Stochastic differential equation	Definition	Probability theory and stochastic processes
Abelian category	Concept	Category theory; homological algebra
Affine variety	Definition	Algebraic geometry
Rigid analytic space	Concept	Algebraic geometry
Branched covering	Concept	Manifolds and cell complexes
Dirichlet eigenvalue	Definition	Partial differential equations
Lattice of subvarieties	Definition	General algebraic systems
Euler's continued fraction formula	Theorem	Sequences, series, summability
Fractional ideal	Concept	Commutative algebra
Ree groups	Object	Group theory and generalizations
Sz.-Nagy's dilation theorem	Theorem	Operator theory
Grushko theorem	Theorem	Group theory and generalizations
Voter model	Example	Probability theory and stochastic processes
Thurston norm	Definition	Manifolds and cell complexes
Kadomtsev–Petviashvili equation	Definition	Partial differential equations
Schottky group	Concept	Functions of a complex variable
Order filter	Definition	Order, lattices, ordered algebraic structures
Zariski's lemma	Lemma	Commutative algebra
Buchberger's algorithm	Definition	Commutative algebra
Evolute	Definition	Differential geometry
Hessenberg matrix	Concept	Linear and multilinear algebra; matrix theory
Boundary layer	Concept	Ordinary differential equations
Homology with coefficients	Definition	Algebraic topology
Homotopy groups of spheres	Concept	Algebraic topology
Dini derivative	Definition	Real functions
Artin–Schreier theorem on formally real fields	Theorem	Field theory and polynomials
Amitsur–Levitzki theorem	Theorem	Associative rings and algebras
Going-down theorem	Theorem	Commutative algebra
Mazur–Orlicz theorem	Theorem	Sequences, series, summability
Stationary set	Concept	Mathematical logic and foundations
Hill differential equation	Example	Ordinary differential equations
Bieberbach theorems	Theorem	Group theory and generalizations
Sturm separation theorem	Theorem	Ordinary differential equations
Nagata's example of a Noetherian ring of infinite dimension	Counterexample	Commutative algebra
von Neumann bounded set	Definition	Functional analysis
HNN extension	Concept	Group theory and generalizations
Quasi-analytic function	Concept	Real functions
Unirational variety	Concept	Algebraic geometry
Limit set	Concept	Dynamical systems and ergodic theory
Excellent ring	Concept	Commutative algebra
Zero morphism	Concept	Category theory; homological algebra
Generalized cohomology theory	Definition	Algebraic topology
Isomorphism theorem for measure algebras	Theorem	Measure and integration
Hilbert's Theorem 90	Theorem	Field theory and polynomials
Order of a PDE	Definition	Partial differential equations
Malcev completion	Definition	Topological groups, Lie groups
Birkhoff–Frink representation of algebraic closure systems	Theorem	General algebraic systems
(∞,1)-category	Concept	Category theory; homological algebra
Uniform boundedness principle	Theorem	Functional analysis
Finite field arithmetic	Concept	Field theory and polynomials
Dissipative operator	Definition	Operator theory
Choquet capacity	Definition	Measure and integration
Operator theory	Concept	Operator theory
Projective object	Definition	Category theory; homological algebra
Heat kernel	Definition	Partial differential equations
Quantum invariant of 3-manifolds	Concept	Manifolds and cell complexes
Reflexive operator algebra	Definition	Operator theory
Gromov's compactness theorem	Theorem	Differential geometry
A Dedekind UFD is a PID	Proposition	Commutative algebra
Finitely based algebra	Concept	General algebraic systems
Triangulation	Concept	Manifolds and cell complexes
Semilocal ring	Definition	Associative rings and algebras
One-parameter subgroup	Concept	Topological groups, Lie groups
Langlands classification	Theorem	Topological groups, Lie groups
Poincaré–Lindstedt method	Concept	Ordinary differential equations
Eilenberg–Steenrod axioms	Concept	Algebraic topology
Doob decomposition theorem	Theorem	Probability theory and stochastic processes
Symmetric decreasing rearrangement	Definition	Real functions
Combinatorics on words	Concept	Computer science
WKB approximation	Concept	Ordinary differential equations
Ramification group	Definition	Number theory
Analytic combinatorics	Concept	Combinatorics
Wedderburn's theorem on simple Artinian rings	Theorem	Associative rings and algebras
Ruled surface	Definition	Algebraic geometry
Commuting elements	Concept	General algebraic systems
Inverse Galois problem	Problem	Field theory and polynomials
Mirror symmetry	Concept	Algebraic geometry
Kauffman bracket	Definition	Manifolds and cell complexes
Theorema Egregium	Theorem	Differential geometry
Developable surface	Concept	Differential geometry
Rellich–Kondrachov theorem	Theorem	Functional analysis
Oscillation of a function	Definition	Real functions
Site	Definition	Category theory; homological algebra
Bredon cohomology	Concept	Algebraic topology
Incidence matrix	Definition	Combinatorics
Harnack's inequality	Theorem	Potential theory
Gumm terms	Definition	General algebraic systems
Nonassociative ring	Concept	Nonassociative rings and algebras
Chevalley group	Concept	Group theory and generalizations
Integer factorization	Problem	Number theory
Subfactor	Definition	Functional analysis
1 + 1 + 1 + 1 + ⋯	Example	Sequences, series, summability
Hurwitz zeta function	Definition	Number theory
Locally finite measure	Concept	Measure and integration
Finitely presented module	Definition	Commutative algebra
Commutant	Definition	Functional analysis
Artinian module	Concept	Associative rings and algebras
Hahn series	Concept	Commutative algebra
Observability	Definition	Systems theory; control
Diagonally dominant matrix	Definition	Linear and multilinear algebra; matrix theory
Controllability	Definition	Systems theory; control
Model complete theory	Concept	Mathematical logic and foundations
Functional differential equation	Definition	Ordinary differential equations
Koszul algebra	Definition	Associative rings and algebras
Integro-differential equation	Concept	Integral equations
Adapted process	Concept	Probability theory and stochastic processes
Order of an entire function	Definition	Functions of a complex variable
Tarski's undefinability theorem	Theorem	Mathematical logic and foundations
Gaussian binomial coefficient	Concept	Combinatorics
Lambert summation	Definition	Sequences, series, summability
Fuchsian equation	Definition	Ordinary differential equations
Compact quantum group	Definition	Functional analysis
Product order	Definition	Order, lattices, ordered algebraic structures
Nevanlinna characteristic	Concept	Functions of a complex variable
Classifying topos	Definition	Category theory; homological algebra
Vaught conjecture	Conjecture	Mathematical logic and foundations
Continuous and residual spectrum	Concept	Operator theory
Surreal number	Object	Order, lattices, ordered algebraic structures
Valuation ring	Definition	Commutative algebra