Isomorphism Preserves Associativity/Proof 2
Theorem
Let $\struct {S, \circ}$ and $\struct {T, *}$ be algebraic structures.
Let $\phi: \struct {S, \circ} \to \struct {T, *}$ be an isomorphism.
Then $\circ$ is associative if and only if $*$ is associative.
Proof
An isomorphism is a fortiori an epimorphism.
The result follows from Epimorphism Preserves Associativity.
$\blacksquare$