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Homotopy Type Theory
commutant > history (Rev #1)

## Definition

Let $(A, m)$ be a magma and let $B$ be a subtype of $A$ with a monic function $i:B \subseteq A$.

The **commutant** of $B$ in $A$ is defined as

$C_A(B) \coloneqq \sum_{b:B} \prod_{a:A} m(a, i(b)) = m(i(b), a)$

The **center** or **centre** of $A$ is defined as the commutant of $A$ in $A$

$Z(A) \coloneqq C_A(A)$

## See also

Revision on March 14, 2022 at 22:13:48 by
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