Coherence is, in general, a state or situation in which all the parts or ideas fit together well so that they form a united whole. More specifically, coherence, coherency, or coherent may refer to the following:

Physics

Coherence (physics) Coherence expresses the potential for two waves to Wave interference, interfere. Two Monochromatic radiation, monochromatic beams from a single source always interfere. Wave sources are not strictly monochromatic: they may be ''partly coherent''. ...

, an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference *

Coherence (units of measurement) A coherent system of units is a system of units of measurement used to express physical quantities that are defined in such a way that the equations relating the numerical values expressed in the units of the system have exactly the same form, in ...

, a derived unit that, for a given system of quantities and for a chosen set of base units, is a product of powers of base units with no other proportionality factor than one *

Coherence time For an electromagnetic wave, the coherence time is the time over which a propagating wave (especially a laser or maser beam) may be considered coherent, meaning that its phase is, on average, predictable. In long-distance transmission systems ...

, the time over which a propagating wave (especially a laser or maser beam) may be considered coherent; the time interval within which its phase is, on average, predictable

Mathematics

Coherence (philosophical gambling strategy) In decision theory, economics, and probability theory, the Dutch book arguments are a set of results showing that agents must satisfy the axioms of rational choice to avoid a kind of self-contradiction called a Dutch book. A Dutch book, some ...

, a concept in Bayesian statistics *

Coherence (signal processing) In signal processing, the coherence is a statistic that can be used to examine the relation between two signals or data sets. It is commonly used to estimate the power transfer between input and output of a linear system. If the signals are ergod ...

, a statistic that can be used to examine the relation between two signals or data sets * Coherence (statistics), a property of self-consistency across a set of assessments, or the strength of association between two series *

Coherence condition In mathematics, specifically in homotopy theory and (higher) category theory, coherency is the standard that equalities or diagrams must satisfy when they hold "up to homotopy" or "up to isomorphism". The adjectives such as "pseudo-" and "lax-" ...

in category theory, a collection of conditions requiring that various compositions of elementary morphisms are equal *

Coherency (homotopy theory) In mathematics, specifically in homotopy theory and (higher) category theory, coherency is the standard that equalities or diagrams must satisfy when they hold "up to homotopy" or "up to isomorphism". The adjectives such as "pseudo-" and "lax-" a ...

in homotopy theory and (higher) category theory *

Coherent sampling Coherence is, in general, a state or situation in which all the parts or ideas fit together well so that they form a united whole. More specifically, coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics ...

, a relationship used in Fast Fourier transforms *

Coherent set of characters In mathematical representation theory, coherence is a property of sets of characters that allows one to extend an isometry from the degree-zero subspace of a space of characters to the whole space. The general notion of coherence was developed by , ...

in representation theory, a property of sets of characters that allows one to extend an isometry from the degree-zero subspace of a space of characters to the whole space *

Coherent sheaf In mathematics, especially in algebraic geometry and the theory of complex manifolds, coherent sheaves are a class of sheaves closely linked to the geometric properties of the underlying space. The definition of coherent sheaves is made with refer ...

, a specific class of sheaves having particularly manageable properties closely linked to the geometrical properties of the underlying space *

Mutual coherence (linear algebra) In linear algebra, mutual coherence (or simply coherence) measures the maximum similarity between any two columns of a matrix, defined as the largest absolute value of their cross-correlations. First explored by David Donoho and Xiaoming Huo in th ...

, sometimes referred to as coherence, the maximum absolute value of the cross-correlations between the columns of a matrix * Multi-spectral phase coherence, a generalized nonlinear cross-frequency phase coupling metric introduced by Yang et al., 2016 *

Coherence (fairness) Coherence, also called uniformity or consistency, is a criterion for evaluating rules for fair division. Coherence requires that the outcome of a fairness rule is fair not only for the overall problem, but also for each sub-problem. Every part of ...

, a consistency requirement of fair division rules. * Coherent topology, topology determined by a family of subspaces.

Philosophy

Coherentism In philosophical epistemology, there are two types of coherentism: the coherence theory of truth, and the coherence theory of justification (also known as epistemic coherentism). Coherent truth is divided between an anthropological approach, w ...

, philosophical theories in modern epistemology, the study of knowledge *

Coherence theory of truth Coherence theories of truth characterize truth as a property of whole systems of propositions that can be ascribed to individual propositions only derivatively according to their coherence with the whole. While modern coherence theorists hold that ...

, a theory which regards truth as coherence within some specified set of sentences, propositions or beliefs

Computer science

Coherence (programming language) Subtext is a moderately visual programming language and environment, for writing application software. It is an experimental, research attempt to develop a new programming language, programming model, called Example Centric Programming, by treatin ...

, an experimental programming language based upon Subtext *

Cache coherence In computer architecture, cache coherence is the uniformity of shared resource data that is stored in multiple local caches. In a cache coherent system, if multiple clients have a cached copy of the same region of a shared memory resource, all ...

, a special case of memory coherence *

Memory coherence Memory coherence is an issue that affects the design of computer systems in which two or more Central processing unit, processors or Multi core, cores share a common area of memory (computers), memory. In a uniprocessor system (where there exists o ...

, a concept in computer architecture * In scrum and agile methodologies,

coherence Coherence is, in general, a state or situation in which all the parts or ideas fit together well so that they form a united whole. More specifically, coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics ...

is defined as a measure of the relationships between backlog items which make them worthy of consideration as a whole.

IT products

Coherence (software) Parallels Desktop for Mac is a hypervisor providing hardware virtualization for Mac (computer), Mac computers. It is developed by Parallels (company), Parallels, a subsidiary of Corel. Parallels was initially developed for Macintosh systems with ...

, a component of Parallels Desktop for Mac, the Windows virtualization software *

Coherent (operating system) Coherent is a clone of the Unix operating system for IBM PC compatibles and other microcomputers, developed and sold by the now-defunct Mark Williams Company (MWC). Historically, the operating system was a proprietary product, but it became Op ...

, a UNIX-clone operating system *

Oracle Coherence In computing, Oracle Coherence (originally Tangosol Coherence) is a Java-based distributed cache and in-memory data grid. It is claimed to be intended for systems that require high availability, high scalability and low latency, particularly in ca ...

, an in-memory data grid product from Oracle

Other uses

Coherence (cognitive science) Coherence theories of truth characterize truth as a property of whole systems of propositions that can be ascribed to individual propositions only derivatively according to their coherence with the whole. While modern coherence theorists hold that ...

, a property of mental/cognitive states *

Coherence (linguistics) Coherence in linguistics is what makes a text semantically meaningful. It is especially dealt with in text linguistics. Coherence is achieved through syntactic features such as the use of deictic, anaphoric and cataphoric elements or a logical ...

, what makes a text semantically meaningful *

Coherence (music theory) In diatonic set theory, Rothenberg propriety is an important concept, lack of contradiction and ambiguity, in the general theory of musical scales which was introduced by David Rothenberg in a seminal series of papers in 1978. The concept was in ...

, a synonym for strict Rothenberg propriety in diatonic set theory *

Coherent optical module Coherent optical module refers to a typically hot-pluggable coherent optical transceiver that uses coherent modulation ( BPSK/QPSK/ QAM) rather than amplitude modulation (RZ/ NRZ/ PAM4) and is typically used in high-bandwidth data communications ap ...

, a hot-pluggable optical transceiver implementing a coherent modulation algorithm *

Coherence time (communications systems) In communications systems, a communication channel may change with time. Coherence time is the time duration over which the channel impulse response is considered to be not varying. Such channel variation is much more significant in wireless comm ...

, duration when a communication channel can be assumed to be constant * Coherent, Inc., a company specializing in equipment to make and measure coherent light (lasers) *

Coherent risk measure In the fields of actuarial science and financial economics there are a number of ways that risk can be defined; to clarify the concept theoreticians have described a number of properties that a risk measure might or might not have. A coherent ris ...

in financial economics, a function that satisfies properties of monotonicity, sub-additivity, homogeneity, and translational invariance * ''Coherence'' (film), a 2013 science fiction film by James Ward Byrkit * Sense of coherence, a construct in the health theory

salutogenesis Salutogenesis is the study of the origins (''genesis'') of health (''salus'') and focuses on factors that support human health and well-being, rather than on factors that cause disease (pathogenesis). More specifically, the "salutogenic model" w ...