Invariant
# Invariant

Invariant and invariance may refer to:

## Computer science

* Invariant (computer science), an expression whose value doesn't change during program execution
   * Loop invariant, a property of a program loop that is true before (and after) each iteration
* A data type in method overriding that is neither covariant nor contravariant
* Class invariant, an invariant used to constrain objects of a class

## Physics, mathematics, and statistics

* Invariant (mathematics), a property of a mathematical object that is not changed by a specific operation or transformation
   * Rotational invariance, the property of function whose value does not change when arbitrary rotations are applied to its argument
   * Scale invariance, a property of objects or laws that do not change if scales of length, energy, or other variables, are multiplied by a common factor
   * Topological invariant
* Invariant (physics), something does not change under a transformation, such as from one reference frame to another
* Invariant estimator in statistics
* Measurement invariance, a statistical property of measurement
* Oxford University Invariant Society, an Oxford student mathematics club

## 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
* Invariances, a 2001 book by philosopher Robert Nozick
