Invariant

Invariant and invariance may have several meanings, among which are:

Computer science

• Invariant (computer science), an expression whose value doesn't change during program execution
  • Loop invariant, invariants used to prove properties of loops
• A data type in method overriding that is neither covariant nor contravariant
• Class invariant, invariants used to constrain objects of a class

Mathematics

• Invariant (mathematics), something unaltered by a transformation, for example: taking a homotopy group functor on the category of topological spaces. Then, homeomorphic spaces have isomorphic fundamental group.
  • topological invariant
• Invariant (physics), meaning that something does not change under a transformation, such as from one reference frame to another
• The Invariant Society, the Oxford student mathematics society

Other uses

• Invariant (linguistics), a word that does not undergo inflection
• Invariant (music)
• Writer invariant, property of a text which is similar in all texts of a given author, and different in texts of different authors
• Invariance (magazine), a French Communist journal