compound
\\[0ex]IsMonHom\{$M_{1}$,$M_{2}$\}($f$) $\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$FunThru2op($\mid$$M_{1}$$\mid$;$\mid$$M_{2}$$\mid$;$\ast$$M_{1}$;$\ast$$M_{2}$;$f$) \& $f$(e$M_{1}$) = (e$M_{2}$) $\in$ $\mid$$M_{2}$$\mid$