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RingHom($R$;$S$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\{\=$f$:$\mid$$R$$\mid\rightarrow\mid$$S$$\parallel$ \+
\\[0ex]FunThru2op($\mid$$R$$\mid$;$\mid$$S$$\mid$;+$R$;+$S$;$f$) \& FunThru2op($\mid$$R$$\mid$;$\mid$$S$$\mid$;$\ast$$R$;$\ast$$S$;$f$) \& $f$(1$R$) = (1$S$) $\in$ $\mid$$S$$\mid$\} 
\-
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