Transitive: For binary structures $$S$1,,$S$2,$ and $$S$3,,$ if

S$1\text{'}$ S$2$ and S$2\text{'}$ S$3$ then S$1\text{'}$ S$3.$ Hint: assume $\backslash$phi $1$ : S$1->$ S$2$

and $\backslash$phi $2$ : S$2->$ S$3$ are isomorphisms and prove that $\backslash$phi $2\backslash$phi $1$ : S$1->$

S$3$ is also an isomorphism.