proposition: Lemma eval_zero_inv: forall n m z, eval n m U.zero z -> z=0.
proof: Proof. intros. dependent destruction H. auto. Qed.
imports: ATBR(MyFSets MyFSetProperties) ATBR(Common) ATBR(Classes) ATBR(Graph) ATBR(Monoid) ATBR(SemiLattice) ATBR(Numbers) ATBR(Reification)