Draft:Congruence

Congruence (symbol: ≅) is a concept in various fields describing a state achieved by coming together, the state of agreement. The word is derived from the Latin congruō meaning "I meet together, I agree". As an abstract term, congruence means similarity between objects, and in this context it has been noted that "the concept of congruence plays an important role within the theoretical description of our world". Congruence, as opposed to approximation, is a relation which implies a species of equivalence. In various social situations, such as the design of business organizations, "congruence is a measure of how well pairs of components fit together".

"[T]he relation of congruence that holds between objects that are divided spatially is undetermined unless the concept of congruence has been fixed by definitions. In this sense, the definition may again be called a “logical presupposition concerning measurements”. And since it is achieved by a coordination of the concept of congruence with “a real object”, here again we have a case of a coordinative definition".

Congruence may "refer indifferently to any species of metrical equality". One source describes congruence as encompassing "three major properties: consistency, reciprocity, and coherence".

A 2019 article reported that "studies which investigated the interaction of different styles or genres of music and visual arts (e.g., paintings and architecture) have found that the stylistic congruence between paintings and music increased the aesthetic evaluation".

Mathematics
In geometry, two figures or objects are congruent if they have the same shape and size, or if one has the same shape and size as the mirror image of the other.


 * Congruence or congruence relation, in abstract algebra, an equivalence relation on an algebraic structure that is compatible with the structure
 * In modular arithmetic, having the same remainder when divided by a specified integer
 * Ramanujan's congruences, congruences for the partition function, $p(n)$, first discovered by Ramanujan in 1919
 * Congruence subgroup, a subgroup defined by congruence conditions on the entries of a matrix group with integer entries
 * Congruence of squares, in number theory, a congruence commonly used in integer factorization algorithms
 * Matrix congruence, an equivalence relation between two matrices
 * Congruence (manifolds), in the theory of smooth manifolds, the set of integral curves defined by a nonvanishing vector field defined on the manifold
 * Congruence (general relativity), in general relativity, a congruence in a four-dimensional Lorentzian manifold that is interpreted physically as a model of space time, or a bundle of world lines
 * Zeller's congruence, an algorithm to calculate the day of the week for any date
 * Scissors congruence, a property of polyhedra that can be cut into finitely many polyhedral pieces and reassembled into each other, related to Hilbert's third problem

Mineralogy and chemistry
In mineralogy and chemistry, the term congruent (or incongruent) may refer to:


 * Congruent dissolution: substances dissolve congruently when the composition of the solid and the dissolved solute stoichiometrically match
 * Congruent melting occurs during melting of a compound when the composition of the liquid that forms is the same as the composition of the solid
 * Incongruent transition, in chemistry, is a mass transition between two phases which involves a change in chemical composition

Psychology

 * In Carl Rogers' personality theory, the compliance between ideal self and actual self. See Carl Rogers.
 * Mood congruence between feeling or emotion (in psychiatry and psychology)

The incongruity theory of humor proposes that incongruity is a key aspect of certain expressions of humor. Aristotle observed that many jokes relied on a combination of incongruity and hostility. He explained that jokes are funny because they catch the listener off guard, introducing a surprising and unexpected twist that amuses them. However, this incongruity alone does not entirely explain the mechanics of laughter. There also appears to be a component of hostility from both the comedian and the audience. What makes something funny often involves ridiculous features, such as a physical deformity or a slip-up. Therefore, whether through jokes, situations, or physical characteristics, while humor's laughter-inducing quality primarily stems from incongruity, aggression is also intertwined with it.