Congruence

• Congruence (geometry), being the same size and shape • 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, , 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 spacetime or a bundle of world lines • Zeller's congruence, an algorithm to calculate the day of the week for any date • Scissors congruence, 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 § Incongruity • Mood congruence between feeling or emotion (in psychiatry and psychology) • Incongruity theory of humor == See also ==