6,052 articles
Hopf fibration
The Hopf fibration is the map from the 3-sphere to the 2-sphere whose fibers are pairwise linked circles, defined by Heinz Hopf in 1931 as the first nontrivial fiber bundle.
Hopf invariant
The Hopf invariant is an integer assigned to the homotopy class of a map between spheres, introduced by Heinz Hopf in 1931 and central to homotopy theory.
Horn clause
A Horn clause, also known as a Horn sentence, is a clause containing at most one positive literal, named after logician Alfred Horn, central to logic programming and Prolog.
Horner's method
Horner's method, also called Horner's rule or Horner's scheme, is an algorithm for evaluating a polynomial by rewriting it in nested form, using only n multiplications and n additions.
Horseshoe prior
The horseshoe prior is a Bayesian shrinkage prior for sparse regression, introduced by Carvalho, Polson, and Scott in 2009, that shrinks noise hard while leaving strong signals unshrunk.
Horvitz–Thompson estimator
The Horvitz–Thompson estimator is a design-based estimator of a population total, introduced in 1952, that weights each sampled unit by the reciprocal of its inclusion probability.
Hot spot analysis
Hot spot analysis is a spatial statistics method that identifies statistically significant clusters of high or low values in geographic data, most commonly with the Getis-Ord Gi statistic.
Hotelling's T-squared distribution
Hotelling's T-squared distribution is the sampling distribution of a statistic measuring a multivariate sample mean's squared distance from a hypothesized value, introduced by Harold Hotelling in 1931.
Household income in the United States
Household income in the United States, also called U.S. household income, is the combined income of all people in a housing unit, measured chiefly by the Census Bureau's surveys.
Household, Income and Labour Dynamics in Australia
The Household, Income and Labour Dynamics in Australia (HILDA) Survey, known to respondents as the Living in Australia Study, has tracked Australian households annually since 2001.
Householder transformation
The Householder transformation, also called a Householder reflection, is a symmetric orthogonal matrix reflecting vectors across a hyperplane, widely used in QR factorization since Alston Householder introduced it in 1958.
How to Solve It
How to Solve It is a 1945 book by the Hungarian mathematician George Pólya setting out a four-phase method for solving problems and a collection of heuristics.
Howell design
A Howell design H(s, 2n) is an s × s array of unordered pairs from 2n symbols, generalizing the Room square used in duplicate bridge scheduling.
HP Prime
The HP Prime is a graphing calculator with a computer algebra system, color multi-touch screen, and rechargeable battery, introduced by Hewlett-Packard in autumn 2013 and still produced in a revised G2 version.
Huber loss
The Huber loss is a loss function in robust regression that is quadratic for small residuals and linear for large ones, limiting the influence of outliers.
Human Mortality Database
The Human Mortality Database (HMD) is a free open-access database of mortality and population data for 41 countries, launched in 2002 and hosted by UC Berkeley and the Max Planck Institute.
Hume's principle
Hume's principle is an abstraction principle in the philosophy of arithmetic stating that numbers of things are equal exactly when the things can be paired one to one.
Hunger games search
Hunger games search (HGS) is a population-based metaheuristic optimization algorithm introduced by Yutao Yang and colleagues in 2021, which uses adaptive hunger weights mimicking animal foraging to find the global optimum of single-objective functions.
Hurdle model
The hurdle model is a two-part regression model for count data with many zeros, combining a binary zero/nonzero process with a zero-truncated count model for positive counts.
Hurst exponent
The Hurst exponent, or Hurst parameter and Hurst coefficient, is a number between 0 and 1 measuring long-range memory in a time series, named for hydrologist Harold Edwin Hurst.
Hurwitz's theorem (composition algebras)
Hurwitz's theorem is Adolf Hurwitz's 1898 classification of real composition algebras: their dimensions are only 1, 2, 4, or 8, namely the reals, complexes, quaternions, and octonions.
Hybrid automaton
A hybrid automaton is a mathematical model combining continuous dynamics described by differential equations with discrete events, extending finite-state machines; it was introduced at Cornell in 1993.
Hybrid logic
Hybrid logic is a family of extensions of modal logic in which formulas can name the possible worlds, times, or states at which they are evaluated.
Hybridizable discontinuous Galerkin method
The hybridizable discontinuous Galerkin (HDG) method is a discontinuous Galerkin finite element method for partial differential equations, reported by Cockburn, Gopalakrishnan, and Lazarov in 2009.
Hydra game
The hydra game is a mathematical process, introduced by Laurie Kirby and Jeff Paris in 1982, in which a player cuts heads from a regrowing tree and always wins.
Hypatia
Hypatia of Alexandria, daughter of the mathematician Theon, was a Greek mathematician, astronomer, and philosopher, the first woman in the history of mathematics, murdered by a mob in 415.
Hyperarithmetic theory
Hyperarithmetic theory is a branch of computability theory introduced in the early 1950s by Davis, Mostowski, and Kleene, characterizing the hyperarithmetical sets via definability and iterated Turing jumps.
Hyperarithmetical theory
Hyperarithmetical theory, which studies the hyperarithmetic sets, or HYP, is the branch of computability theory that iterates the Turing jump through the computable ordinals, a hierarchy begun by Stephen Cole Kleene in the 1950s.
Hyperbola
A hyperbola is a conic section with two open, mirror-image branches, defined by a constant difference of distances to two foci, named by Apollonius of Perga.
Hyperbolic 3-manifold
A hyperbolic 3-manifold is a three-dimensional manifold with a complete Riemannian metric of constant negative curvature, the central object of William Thurston's 1980s geometrization program in topology.