fact: Definition prl_map2_compat S S' u:= [/\ fgraph u, domain u = psI S, forall i, inc i (psI S) -> function_prop (Vg u i) (Vg (psE S) i) (Vg (psE S') i) & forall i j, gle (psr S) i j -> (Vg u i) \co (Vg (psf S) (J i j)) = (Vg (psf S') (J i j)) \co (Vg u j)].
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)