Mathematics and statistics

Convolution quadrature

Convolution quadrature is a numerical method, introduced by C. Lubich in 1988, that approximates convolution integrals on a uniform time grid using only the kernel's Laplace transform.

Convolution theorem

The convolution theorem states that the transform of a convolution of two functions equals the product of their transforms, and underlies FFT-based filtering and deconvolution.

Conway group

The Conway groups are three sporadic simple groups, Co1, Co2, and Co3, discovered by John Conway around 1968 as symmetry groups of the 24-dimensional Leech lattice.

Conway's Game of Life

Conway's Game of Life is a cellular automaton devised by mathematician John Horton Conway, in which simple rules on a grid of cells support universal computation.

Cook–Levin theorem

The Cook–Levin theorem, also called Cook's theorem, is the complexity-theory result that Boolean satisfiability (SAT) is NP-complete, proved independently by Stephen Cook in 1971 and Leonid Levin.

Cook's distance

Cook's distance, also known as Cook's D, is a regression diagnostic measuring how much a model's estimates change when a single observation is deleted and the model is refitted.

Cooperative game theory, also called coalitional game theory, studies how players who can make binding agreements should divide the payoff or cost of joint action, using concepts like the core and the Shapley value.

Coordinate descent

Coordinate descent, also known as the coordinate descent method, is an iterative optimization method that minimizes a function one coordinate at a time while holding the others fixed.

Coordinate system

A coordinate system, also called a system of coordinates, is a set of numbers that specifies the position of a point in a space, as in Cartesian or polar systems.

Coordinate-free

Coordinate-free, also called component-free or basis-free, describes mathematics and programming in which objects and laws are specified intrinsically, so coordinates can be introduced for calculation without becoming part of the object's identity.

Coprime integers

Coprime integers, also called relatively prime, mutually prime, or strangers, are integers whose greatest common divisor is 1, such as 8 and 15; about 61 percent of random pairs are coprime.

Coproduct

A coproduct is a category-theoretic construction that combines objects by mapping into the result, dual to the product and realized as disjoint unions, free products, and direct sums.

Copula (probability theory)

A copula is a function that couples the marginal distributions of several random variables to their joint distribution, capturing dependence separately from each variable's individual behavior.

Copula model

A copula model is a statistical model of dependence among random variables that separates marginals from dependence, widely used in finance, credit risk, and multivariate analysis.

Coq (proof assistant)

Coq, an interactive theorem prover developed at INRIA in France since 1984, underlies the verified CompCert C compiler and was renamed the Rocq Prover in 2025.

Core decomposition

Core decomposition is a graph algorithm that partitions a network's vertices into nested k-cores, subgraphs where every vertex has degree at least k, and assigns each vertex a core number.

Core model

The core model, usually written K, is a canonical inner model of set theory, built by Dodd and Jensen to carry as much large-cardinal structure as a stated bound allows.

COREQ

COREQ (Consolidated Criteria for Reporting Qualitative Research) is a 32-item checklist, published in 2007 by Allison Tong, Peter Sainsbury, and Jonathan Craig, for reporting qualitative interview and focus-group studies.

Corina Tarnita

Corina Tarnita is a Romanian-born American mathematical biologist, Frederick D. Petrie Professor at Princeton University since 2013, known for work on eusociality and termite-driven vegetation patterns.

Cornish–Fisher expansion

The Cornish–Fisher expansion is an asymptotic expansion approximating the quantiles of a near-normal distribution from standard normal quantiles, introduced by E. A. Cornish and Ronald A. Fisher in 1937.

Corrective and preventive action

Corrective and preventive action (CAPA) is a quality management process that finds and fixes product and quality problems and prevents recurrence, required under FDA and ISO rules.

Correlation

Correlation, also called statistical association, is any statistical relationship between two random variables, most commonly Pearson's coefficient, introduced by Francis Galton in 1888 and formulated by Karl Pearson in 1895.

Correlation clustering

Correlation clustering is a graph clustering method that partitions vertices using pairwise similarity labels, introduced by Bansal, Blum, and Chawla in 2004 and used in machine learning.

Correlation coefficient

A correlation coefficient, or coefficient of correlation, is a number between −1 and +1 that measures the linear relationship between two variables, best known as Pearson's r.

Correlation matrix

A correlation matrix is a square, symmetric matrix whose entries give the correlation coefficient between each pair of variables, with ones on the diagonal and off-diagonal values between −1 and 1.

Correspondence analysis

Correspondence analysis is an exploratory multivariate statistical method that maps the associations in a contingency table, plotting its row and column categories in a single low-dimensional plot.

Coset

A coset, left coset or right coset, is a translate gH or Hg of a subgroup H inside a group G; equal-sized cosets partition G, yielding Lagrange's theorem.

Cosine similarity

Cosine similarity is a measure of similarity between two nonzero vectors, the cosine of the angle between them; it runs from 1 for the same direction to -1 for opposite.

Cospectral graphs

Cospectral graphs, also called isospectral graphs, are graphs sharing the same eigenvalue spectrum; their existence shows a spectrum does not uniquely determine a graph's structure.