# invariant

Also found in: Dictionary, Thesaurus, Wikipedia.

## 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**)Want to thank TFD for its existence? Tell a friend about us, add a link to this page, or visit the webmaster's page for free fun content.

Link to this page: