Coherence, coherency, or coherent may refer to the following:

Physics

Coherence (physics) In physics, two wave sources are coherent if their frequency and waveform are identical. Coherence is an ideal property of waves that enables stationary (i.e., temporally or spatially constant) interference. It contains several distinct concep ...

, an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference * Coherence (units of measurement), 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), a concept in Bayesian statistics * Coherence (signal processing), 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, and particularly category theory, a coherence condition is a collection of conditions requiring that various compositions of elementary morphisms are equal. Typically the elementary morphisms are part of the data of the category. ...

in category theory, a collection of conditions requiring that various compositions of elementary morphisms are equal * Coherency (homotopy theory) in homotopy theory and (higher) category theory * Coherent sampling, 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 ref ...

, 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, the coherence or mutual coherence of a matrix ''A'' is defined as the maximum absolute value of the cross-correlations between the columns of ''A''. Formally, let a_1, \ldots, a_m\in ^d be the columns of the matrix ''A'', whic ...

, 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.

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, wh ...

, 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), an experimental programming language based upon Subtext *

Cache coherence In computer architecture, cache coherence is the uniformity of shared resource data that ends up stored in multiple local caches. When clients in a system maintain caches of a common memory resource, problems may arise with incoherent data, wh ...

, a special case of memory coherence * Memory coherence, a concept in computer architecture * In scrum and agile methodologies,

coherence Coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics), an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference * Coherence (units of measurement), a deriv ...

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

IT products

* Coherence (software), a component of Parallels Desktop for Mac, the Windows virtualization software * Coherent (operating system), 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 ...

, 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), what makes a text semantically meaningful *

Coherence (music theory) Coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics), an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference * Coherence (units of measurement), a deriv ...

, a synonym for strict Rothenberg propriety in diatonic set theory * Coherent optical module, 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 commu ...

, duration when a communication channel can be assumed to be constant *

Coherent, Inc. Coherent, Inc., headquartered in Santa Clara, California is an American company that develops, manufactures and supports laser equipment and related specialty components. Coherent was founded in May 1966 by physicist James Hobart and five cofound ...

, 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 ...