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 = 9] f(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f(s(s(s(s(s(s(s(s(id(_0))))))))),_1,_1) Let l be the left-hand side and r be the right-hand side of this rule. Let p = epsilon, theta1 = {} and theta2 = {_0->id(_0)}. We have r|p = f(s(s(s(s(s(s(s(s(id(_0))))))))),_1,_1) and theta2(theta1(l)) = theta1(r|p). Hence, the term theta1(l) = f(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) 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^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(id(s(s(s(s(s(s(s(s(_0))))))))),_1,_1)] TRS = {f(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f(id(s(s(s(s(s(s(s(s(_0))))))))),_1,_1), id(s(_0)) -> s(id(_0)), id(0) -> 0} ## Trying with homeomorphic embeddings... Failed! ## Trying with polynomial interpretations... Too many coefficients (14)! 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, 1 unfolded rule generated. # Iteration 3: nontermination not detected, 1 unfolded rule generated. # Iteration 4: nontermination not detected, 1 unfolded rule generated. # Iteration 5: nontermination not detected, 1 unfolded rule generated. # Iteration 6: nontermination not detected, 1 unfolded rule generated. # Iteration 7: nontermination not detected, 1 unfolded rule generated. # Iteration 8: nontermination not detected, 1 unfolded rule generated. # Iteration 9: nontermination detected, 1 unfolded rule generated. Here is the successful unfolding. Let IR be the TRS under analysis. L0 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(id(s(s(s(s(s(s(s(s(_0))))))))),_1,_1) [trans] is in U_IR^0. We build a unit triple from L0. ==> L1 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(id(s(s(s(s(s(s(s(s(_0))))))))),_1,_1) [unit] is in U_IR^1. Let p1 = [0]. We unfold the rule of L1 forwards at position p1 with the rule id(s(_0)) -> s(id(_0)). ==> L2 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(id(s(s(s(s(s(s(s(_0))))))))),_1,_1) [unit] is in U_IR^2. Let p2 = [0, 0]. We unfold the rule of L2 forwards at position p2 with the rule id(s(_0)) -> s(id(_0)). ==> L3 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(id(s(s(s(s(s(s(_0))))))))),_1,_1) [unit] is in U_IR^3. Let p3 = [0, 0, 0]. We unfold the rule of L3 forwards at position p3 with the rule id(s(_0)) -> s(id(_0)). ==> L4 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(s(id(s(s(s(s(s(_0))))))))),_1,_1) [unit] is in U_IR^4. Let p4 = [0, 0, 0, 0]. We unfold the rule of L4 forwards at position p4 with the rule id(s(_0)) -> s(id(_0)). ==> L5 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(s(s(id(s(s(s(s(_0))))))))),_1,_1) [unit] is in U_IR^5. Let p5 = [0, 0, 0, 0, 0]. We unfold the rule of L5 forwards at position p5 with the rule id(s(_0)) -> s(id(_0)). ==> L6 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(s(s(s(id(s(s(s(_0))))))))),_1,_1) [unit] is in U_IR^6. Let p6 = [0, 0, 0, 0, 0, 0]. We unfold the rule of L6 forwards at position p6 with the rule id(s(_0)) -> s(id(_0)). ==> L7 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(s(s(s(s(id(s(s(_0))))))))),_1,_1) [unit] is in U_IR^7. Let p7 = [0, 0, 0, 0, 0, 0, 0]. We unfold the rule of L7 forwards at position p7 with the rule id(s(_0)) -> s(id(_0)). ==> L8 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(s(s(s(s(s(id(s(_0))))))))),_1,_1) [unit] is in U_IR^8. Let p8 = [0, 0, 0, 0, 0, 0, 0, 0]. We unfold the rule of L8 forwards at position p8 with the rule id(s(_0)) -> s(id(_0)). ==> L9 = f^#(s(s(s(s(s(s(s(s(_0)))))))),_1,_1) -> f^#(s(s(s(s(s(s(s(s(id(_0))))))))),_1,_1) [unit] is in U_IR^9. This DP problem is infinite. ** END proof description ** Proof stopped at iteration 9 Number of unfolded rules generated by this proof = 10 Number of unfolded rules generated by all the parallel proofs = 2378