Covariance and contravariance may refer to:
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Covariance and contravariance of vectors, in mathematics and theoretical physics
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Covariance and contravariance of functors
In mathematics, specifically category theory, a functor is a mapping between categories. Functors were first considered in algebraic topology, where algebraic objects (such as the fundamental group) are associated to topological spaces, and m ...
, in category theory
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Covariance and contravariance (computer science)
Many programming language type systems support subtyping. For instance, if the type is a subtype of , then an expression of type should be substitutable wherever an expression of type is used.
Variance refers to how subtyping between more comp ...
, whether a type system preserves the ordering ≤ of types
See also
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Covariance
In probability theory and statistics, covariance is a measure of the joint variability of two random variables. If the greater values of one variable mainly correspond with the greater values of the other variable, and the same holds for the ...
, in probability theory and statistics, the measure of how much two random variables vary together
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Covariance (disambiguation)
{{Mathematical disambiguation