Definition env_mapsto: forall {key A}{KE: EqDec key} (id: key) (sh: Share.t) (v: A) , pred (env key A) := @_env_mapsto.

Lemma env_mapsto_positive{key: Type}{A: Type}{KE: EqDec key}: forall id sh (v: A) rho, env_mapsto id sh v rho -> nonidentity sh.