invariant

invariant

[in′ver·ē·ənt]

(mathematics)

An element x of a set E is said to be invariant with respect to a group G of mappings acting on E if g (x) = x for all g in G.

A subset F of a set E is said to be invariant with respect to a group G of mappings acting on E if g (x) is in F for all x in F and all g in G.

For an algebraic equation, an expression involving the coefficients that remains unchanged under a rotation or translation of the coordinate axes in the cartesian space whose coordinates are the unknown quantities.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

invariant

(programming)

A rule, such as the ordering of an ordered list or heap, that applies throughout the life of a data structure or procedure. Each change to the data structure must maintain the correctness of the invariant.

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)