Congruence

Congruence may refer to:

==Mathematics== 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