fact: Fixpoint vars {n m} (e: kat_expr n m): list Pred := match e with | e_zer _ _ | e_top _ _ | e_one _ => [] | e_pls x y | e_cap x y | e_ldv x y | e_rdv x y | e_dot x y => union (vars x) (vars y) | e_neg x | e_itr x | e_str x | e_cnv x => vars x | syntax.e_var (inr (_,x)) => lsyntax.vars x | syntax.e_var _ => [] end.
imports: lsyntax ordinal lset positives kat gregex syntax