NO Prover = TRS(tech=GUIDED_UNF_TRIPLES, nb_unfoldings=unlimited, unfold_variables=false, max_nb_coefficients=12, max_nb_unfolded_rules=-1, strategy=LEFTMOST_NE) ** BEGIN proof argument ** The following rule was generated while unfolding the analyzed TRS: [iteration = 5] f(g(0,_0),s(0),g(0,_0)) -> f(g(0,_0),_0,g(0,_0)) Let l be the left-hand side and r be the right-hand side of this rule. Let p = epsilon, theta1 = {_0->s(0)} and theta2 = {}. We have r|p = f(g(0,_0),_0,g(0,_0)) and theta2(theta1(l)) = theta1(r|p). Hence, the term theta1(l) = f(g(0,s(0)),s(0),g(0,s(0))) loops w.r.t. the analyzed TRS. ** END proof argument ** ** BEGIN proof description ** ## Searching for a generalized rewrite rule (a rule whose right-hand side contains a variable that does not occur in the left-hand side)... No generalized rewrite rule found! ## Applying the DP framework... ## Round 1: ## DP problem: Dependency pairs = [f^#(0,s(0),_0) -> f^#(_0,+(_0,_0),_0)] TRS = {+(_0,0) -> _0, +(_0,s(_1)) -> s(+(_0,_1)), f(0,s(0),_0) -> f(_0,+(_0,_0),_0), g(_0,_1) -> _0, g(_0,_1) -> _1} ## Trying with homeomorphic embeddings... Failed! ## Trying with polynomial interpretations... Too many coefficients (20)! Aborting! ## Trying with lexicographic path orders... Failed! ## Trying to prove nontermination by unfolding the dependency pairs with the rules of the TRS # max_depth=20, unfold_variables=false: # Iteration 0: nontermination not detected, 1 unfolded rule generated. # Iteration 1: nontermination not detected, 1 unfolded rule generated. # Iteration 2: nontermination not detected, 7 unfolded rules generated. # Iteration 3: nontermination not detected, 65 unfolded rules generated. # Iteration 4: nontermination not detected, 805 unfolded rules generated. # Iteration 5: nontermination detected, 6983 unfolded rules generated. Here is the successful unfolding. Let IR be the TRS under analysis. L0 = f^#(0,s(0),_0) -> f^#(_0,+(_0,_0),_0) [trans] is in U_IR^0. We build a unit triple from L0. ==> L1 = f^#(0,s(0),_0) -> f^#(_0,+(_0,_0),_0) [unit] is in U_IR^1. Let p1 = [0]. We unfold the rule of L1 backwards at position p1 with the rule g(_0,_1) -> _0. ==> L2 = f^#(g(0,_0),s(0),g(0,_0)) -> f^#(g(0,_0),+(g(0,_0),g(0,_0)),g(0,_0)) [unit] is in U_IR^2. Let p2 = [1, 0]. We unfold the rule of L2 forwards at position p2 with the rule g(_0,_1) -> _1. ==> L3 = f^#(g(0,_0),s(0),g(0,_0)) -> f^#(g(0,_0),+(_0,g(0,_0)),g(0,_0)) [unit] is in U_IR^3. Let p3 = [1, 1]. We unfold the rule of L3 forwards at position p3 with the rule g(_0,_1) -> _0. ==> L4 = f^#(g(0,_0),s(0),g(0,_0)) -> f^#(g(0,_0),+(_0,0),g(0,_0)) [unit] is in U_IR^4. Let p4 = [1]. We unfold the rule of L4 forwards at position p4 with the rule +(_0,0) -> _0. ==> L5 = f^#(g(0,_0),s(0),g(0,_0)) -> f^#(g(0,_0),_0,g(0,_0)) [unit] is in U_IR^5. This DP problem is infinite. ** END proof description ** Proof stopped at iteration 5 Number of unfolded rules generated by this proof = 7862 Number of unfolded rules generated by all the parallel proofs = 13610