fact: Definition fun_set_to_prod src F := Lf (fun f => Lg (domain F)( fun i=> (graph ( (pr_i F i) \co (triple src (productb F) f))))) (gfunctions src (productb F)) (productb (Lg (domain F) (fun i=> gfunctions src (Vg F i)))).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)