Every idea

Ideas 18901–19050 of 19934.

Name	Kind	Subject
Gauss multiplication formula	Theorem	Special functions
Class	Concept	Mathematical logic and foundations
Kirchberger's theorem	Theorem	Convex and discrete geometry
Jefimenko's equations	Theorem	Optics, electromagnetic theory
Multialgebra	Definition	General algebraic systems
Aharonov–Bohm effect	Concept	Quantum theory
Sauer–Shelah lemma	Lemma	Combinatorics
Bilevel optimization	Definition	Operations research, mathematical programming
Parity-check matrix	Concept	Information and communication theory, circuits
Non-atomic measure	Definition	Measure and integration
Class VII surface	Concept	Several complex variables and analytic spaces
Genetic drift	Definition	Biology and other natural sciences
Massive gravity	Concept	Relativity and gravitational theory
Sorgenfrey line	Counterexample	General topology
Thomason–Trobaugh K-theory of schemes	Definition	K-theory
Riccati differential equation of optimal control	Concept	Calculus of variations and optimal control; optimization
Attainable null space	Definition	Functional analysis
Intersection body	Concept	Convex and discrete geometry
Nelder–Mead method	Definition	Operations research, mathematical programming
Eigenvalue perturbation	Definition	Linear and multilinear algebra; matrix theory
Associative quotient of a magma	Definition	Group theory and generalizations
Root pairing	Definition	Nonassociative rings and algebras
Schur–Horn theorem	Theorem	Linear and multilinear algebra; matrix theory
Four-velocity	Concept	Relativity and gravitational theory
Galerkin method	Concept	Numerical analysis
Mal'cev term	Definition	General algebraic systems
Function of exponential order	Definition	Integral transforms, operational calculus
Scleronomous constraint	Concept	Mechanics of particles and systems
Score test	Concept	Statistics
Zoeppritz equations	Definition	Mechanics of deformable solids
Semi-continuity	Definition	Real functions
Cagniard–De Hoop method	Definition	Mechanics of deformable solids
Generic flatness	Theorem	Algebraic geometry
Hurwitz polynomial	Concept	Real functions
Completion of a topological group	Definition	Topological groups, Lie groups
Identical particles	Concept	Quantum theory
Perimeter of a set	Concept	Calculus of variations and optimal control; optimization
Structure	Definition	Mathematical logic and foundations
Divisor class group	Definition	Commutative algebra
Sine and cosine series	Concept	Harmonic analysis on Euclidean spaces
General covariance	Concept	Relativity and gravitational theory
Rural hospitals theorem	Theorem	Game theory, economics, finance, and other social and behavioral sciences
Injectivity radius	Concept	Differential geometry
Glimm scheme	Concept	Partial differential equations
Pseudoconvexity	Definition	Several complex variables and analytic spaces
Numerical range	Definition	Operator theory
Tajima's D	Definition	Statistics
PBR theorem	Theorem	Quantum theory
Castelnuovo–Mumford regularity	Concept	Commutative algebra
Hurewicz fibration	Concept	Algebraic topology
Universal coalgebra	Definition	General algebraic systems
Circle average	Concept	Potential theory
Homogeneity equation	Concept	Difference and functional equations
Nonholonomic system	Definition	Mechanics of particles and systems
de Branges space	Definition	Functional analysis
Lagrange polynomial	Concept	Approximations and expansions
Complex torus	Concept	Algebraic geometry
Flat norm	Concept	Calculus of variations and optimal control; optimization
Bounded symmetric domain	Concept	Several complex variables and analytic spaces
Vandiver's conjecture and K-theory of the integers	Conjecture	Number theory
Canonical height	Definition	Dynamical systems and ergodic theory
Cheeger constant	Concept	Combinatorics
Lie operad	Object	Category theory; homological algebra
CHSH inequality	Theorem	Quantum theory
Brody hyperbolicity	Concept	Several complex variables and analytic spaces
Voigt and Reuss bounds	Theorem	Mechanics of deformable solids
Kerr effect	Concept	Optics, electromagnetic theory
Hypergeometric differential equation	Definition	Special functions
Exponential map	Concept	Differential geometry
Rewriting system	Concept	Computer science
Shannon entropy	Concept	Information and communication theory, circuits
Poroelasticity	Definition	Mechanics of deformable solids
Hermitian K-theory	Definition	K-theory
Non-uniform rational B-spline	Concept	Numerical analysis
Brauer–Manin obstruction	Definition	Algebraic geometry
Nordström's theory of gravitation	Definition	Relativity and gravitational theory
Ratio and root limits give the radius of convergence	Theorem	Functions of a complex variable
Prime knot	Definition	Manifolds and cell complexes
Subgame perfect equilibrium	Definition	Game theory, economics, finance, and other social and behavioral sciences
Faraday's law of induction	Fact	Optics, electromagnetic theory
Infinite compositions of functions	Definition	Sequences, series, summability
Positive-real function	Concept	Systems theory; control
Second-order arithmetic	Definition	Mathematical logic and foundations
Hodge structure	Definition	Algebraic geometry
Hazard function	Concept	Statistics
Continuous and residual spectrum	Definition	Operator theory
E-theory	Concept	K-theory
Measure with density	Concept	Measure and integration
Germ	Definition	General topology
Stochastic differential equation	Definition	Probability theory and stochastic processes
Beta reduction	Concept	Mathematical logic and foundations
Abelian category	Concept	Category theory; homological algebra
Girard's theorem	Theorem	Geometry
Stieltjes moment problem	Problem	Integral transforms, operational calculus
Elliott's classification of AF algebras	Theorem	Functional analysis
NK model	Definition	Biology and other natural sciences
Newton's theorem of revolving orbits	Theorem	Mechanics of particles and systems
Affine variety	Definition	Algebraic geometry
Mathematical biology	Concept	Biology and other natural sciences
Permutation test	Definition	Statistics
Bertrand competition	Concept	Game theory, economics, finance, and other social and behavioral sciences
Sedenions	Object	Nonassociative rings and algebras
Rigid analytic space	Concept	Algebraic geometry
Inverse Compton scattering	Definition	Astronomy and astrophysics
Minkowski–Hlawka theorem	Theorem	Number theory
Branched covering	Concept	Manifolds and cell complexes
Structure constants	Definition	Nonassociative rings and algebras
Dirichlet eigenvalue	Definition	Partial differential equations
Lattice of subvarieties	Definition	General algebraic systems
Decision problem	Concept	Computer science
Adjoint representation of a Lie algebra	Definition	Nonassociative rings and algebras
Euler's continued fraction formula	Theorem	Sequences, series, summability
Fundamental theorem of algebraic K-theory	Theorem	K-theory
Planetary boundary layer	Definition	Geophysics
Fractional ideal	Concept	Commutative algebra
Interaction picture	Definition	Quantum theory
Ree groups	Object	Group theory and generalizations
Hellinger distance	Definition	Statistics
Sz.-Nagy's dilation theorem	Theorem	Operator theory
Incomplete gamma function	Concept	Special functions
Grushko theorem	Theorem	Group theory and generalizations
Fisher's exact test	Definition	Statistics
Voter model	Example	Probability theory and stochastic processes
Thurston norm	Definition	Manifolds and cell complexes
Böttcher's equation	Theorem	Dynamical systems and ergodic theory
Kadomtsev–Petviashvili equation	Definition	Partial differential equations
Sharkovskii's theorem	Theorem	Dynamical systems and ergodic theory
Schottky group	Concept	Functions of a complex variable
Proof of the product formula for the order of HK by counting pairs	Proof	Group theory and generalizations
Order filter	Definition	Order, lattices, ordered algebraic structures
Lorenz gauge condition	Concept	Optics, electromagnetic theory
Zariski's lemma	Lemma	Commutative algebra
Balinski's theorem	Theorem	Convex and discrete geometry
Transitivity of the pair relation for constructing the integers	Lemma	Number theory
Spin	Concept	Quantum theory
q-gamma function	Definition	Special functions
Richardson number	Definition	Fluid mechanics
Prefix code	Definition	Information and communication theory, circuits
Sierpiński's theorem on measurable midpoint convex functions	Theorem	Real functions
Approximation by convolution with mollifiers	Theorem	Functional analysis
Buchberger's algorithm	Definition	Commutative algebra
Evolute	Definition	Differential geometry
Star–triangle relation	Proposition	Statistical mechanics, structure of matter
Hessenberg matrix	Concept	Linear and multilinear algebra; matrix theory
Boundary layer	Concept	Ordinary differential equations
Integral transform	Concept	Integral transforms, operational calculus
Hilbert's twenty-third problem	Problem	Calculus of variations and optimal control; optimization
Homology with coefficients	Definition	Algebraic topology
Algebraic K-theory of spaces	Definition	K-theory
Abscissa of absolute convergence	Concept	Integral transforms, operational calculus