Module VeriStar.
Inductive veristar_result :=
| Valid : veristar_result
| C_example : model -> veristar_result
| Aborted : list clause -> clause -> veristar_result.
Definition pureb c := match c with PureClause _ _ _ _ => true | _ => false end.
Definition pure_clauses := filter pureb.
Definition is_empty_clause (c : clause) :=
match c with PureClause nil nil _ _ => true | _ => false end.
Definition pures := M.filter pureb.

Lemma Ppred_decrease n :
(n<>1)%positive -> (nat_of_P (Ppred n)<nat_of_P n)%nat.