Hint Resolve writable_readable.

(* Specifications: *)
Lemma top_pfullshare: forall psh, pshare_sh psh = Share.top -> psh = pfullshare.
Lemma fst_split_fullshare_not_bot: fst (Share.split fullshare) <> Share.bot.
Lemma fst_split_fullshare_not_top: fst (Share.split fullshare) <> Share.top.
Lemma glb_Rsh_not_top:
forall sh, Share.glb Share.Rsh sh <> Share.top.