6,052 articles
Reed–Solomon error correction
Reed–Solomon error correction is a family of error-correcting codes, introduced by Irving Reed and Gustave Solomon in 1960, used in QR codes, CDs, and spacecraft.
Reeds–Shepp curve
A Reeds–Shepp curve is the shortest path between two oriented points in the plane for a car-like vehicle with a minimum turning radius that can drive both forwards and backwards.
Reflected Brownian motion
Reflected Brownian motion, also called regulated Brownian motion, is a Markov process behaving like Brownian motion in a domain but pushed back at its boundary.
Reflection equation algebra
A reflection equation algebra is a quadratic associative algebra built from matrix solutions of the reflection equation, which describes particle scattering from a boundary in integrable systems.
Reflection principle
A reflection principle in set theory states that any first-order statement true of the universe of sets V is already true in some smaller set-sized Vα.
Reflection principles
A reflection principle is a formal schema asserting that a theory is sound, meaning every sentence it proves is true; it extends theories beyond what they can prove about themselves.
Reflection symmetry
Reflection symmetry, also called line symmetry or reflective symmetry, is the invariance of an object or pattern under reflection across a fixed line or plane of symmetry.
Reflexive operator algebra
A reflexive operator algebra is an algebra of bounded operators equal to the algebra of all operators sharing its invariant subspaces, a notion tied to the invariant subspace problem.
Reflexive relation
A reflexive relation, also called the reflexive property, is a binary relation on a set in which every element is related to itself, as with the identity relation.
Reflexive space
A reflexive space is a Banach space that coincides with its second dual under the canonical embedding, so that its closed unit ball is weakly compact.
Regenerative process
A regenerative process is a stochastic process with random regeneration points at which it becomes a probabilistic replica of itself, producing independent, identically distributed cycles used in steady-state analysis.
Register machine
A register machine is an abstract computing model, developed in the 1960s, whose registers hold non-negative integers; it is Turing equivalent and defines the same computable functions as Turing machines.
Regress argument (epistemology)
The regress argument, or epistemic regress, is a problem in epistemology holding that every chain of justifying reasons must end in basic beliefs, circle, or continue forever.
Regression analysis
Regression analysis, also known as statistical regression, is a set of statistical methods for estimating the relationship between a dependent variable and one or more predictors.
Regression calibration
Regression calibration is a statistical method for correcting bias from measurement error in a covariate, replacing it with its conditional expectation given the observed data before running the usual regression analysis.
Regression discontinuity design
The regression discontinuity design (RDD), introduced by Thistlethwaite and Campbell in 1960, estimates causal effects by comparing units just above and below a treatment cutoff.
Regression estimator (survey sampling)
The regression estimator, including the generalized regression (GREG) estimator, is a survey sampling estimator of a population total that improves precision by using known auxiliary totals.
Regression kriging
Regression kriging, also called residual kriging, is a hybrid spatial prediction method that fits a regression on covariates and kriges the residuals, widely used in digital soil mapping.
Regression toward the mean
Regression toward the mean, also called reversion to the mean, is the statistical phenomenon in which an extreme measurement is followed, on average, by a less extreme one.
Regression tree
A regression tree is a statistical and machine-learning method that predicts a continuous outcome by recursively partitioning data into regions and predicting the mean response in each region.
Regula falsi
Regula falsi, also called the method of false position, is a bracketing root-finding algorithm that uses the secant line through two points straddling a root.
Regular cardinal
A regular cardinal is an infinite cardinal whose cofinality equals itself, meaning it cannot be written as a union of fewer smaller sets; others are singular.
Regular chain (algebra)
In computer algebra, a regular chain is a triangular set of polynomials whose leading coefficients are regular modulo the saturated ideal of earlier polynomials, introduced by Kalkbrener in 1991.
Regular dodecahedron
The regular dodecahedron, also called the pentagonal dodecahedron, is one of the five Platonic solids, with 12 pentagonal faces, 30 edges, and 20 vertices; its dual is the icosahedron.
Regular graph
A regular graph is a simple, undirected graph in which every vertex has the same number of neighbors, its degree k; a k-regular graph exists exactly when nk is even.
Regular icosahedron
The regular icosahedron, or gyroelongated pentagonal bipyramid, is one of the five Platonic solids, a convex polyhedron with 20 equilateral triangular faces, 30 edges, and 12 vertices, with five faces meeting at each vertex.
Regular language
A regular language, also called a rational language, is a set of strings recognizable by a finite automaton, the lowest level of the Chomsky hierarchy.
Regular local ring
A regular local ring is a commutative Noetherian local ring whose maximal ideal can be generated by as many elements as its Krull dimension, making it algebraically smooth.
Regular matroid
A regular matroid is a matroid representable by a totally unimodular matrix, one whose subdeterminants are all 0, 1, or −1, making it representable over every field.
Regular octahedron
The regular octahedron is one of the five Platonic solids, with eight equilateral triangular faces, six vertices, and twelve edges, and the cube as its dual.