compound
rng_hom_p(r;s;f) == FunThru2op(|r|;|s|;+r;+s;f) & FunThru2op(|r|;|s|;*;*;f) & f(1) = 1 

latex

---

clarification:

compound
rng_hom_p(r;s;f)
== FunThru2op(|r|;|s|;+r;+s;f) & FunThru2op(|r|;|s|;*r;*s;f) & f(1r) = (1s)  |s| 

latex

Up	rings 1
Wellformedness Lemmas	rng hom p wf
Definitions	+r, P & Q, FunThru2op(A;B;opa;opb;f), *, |r|, 1