Definition:Entropic Structure

Definition
An entropic structure is an algebraic structure $\left({S, \circ}\right)$ such that $\circ$ is an entropic operation.

That is, such that:
 * $\forall a, b, c, d \in S: \left({a \circ b}\right) \circ \left({c \circ d}\right) = \left({a \circ c}\right) \circ \left({b \circ d}\right)$