fact: Fixpoint valid_heaps i t := match t with Pts _ _ :: s => valid_heaps i s | Var v :: s => (v < size (heap_ctx i)) && valid_heaps i s | _ => true end.
imports: mathcomp(ssreflect ssrbool ssrnat ssrfun eqtype seq) LemmaOverloading(prelude prefix perms heaps)