fact: Definition chain_dp a t u := In a DP /\ exists s, int_red R # t (sub s (lhs a)) /\ u = sub s (rhs a).
imports: Coq(Lia) CoLoR(LogicUtil ATrs ListUtil RelUtil RelSub Path ARelation SN ListOccur ListNodup AShift VecUtil ASubstitution Iter Cycle)