NO Prover = TRS(tech=GUIDED_UNF, nb_unfoldings=unlimited, unfold_variables=true, strategy=LEFTMOST_NE) ** BEGIN proof argument ** The following rule was generated while unfolding the analyzed TRS: [iteration = 2] ap(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),nil)) -> ap(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),nil)) Let l be the left-hand side and r be the right-hand side of this rule. Let p = epsilon, theta1 = {} and theta2 = {}. We have r|p = ap(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),nil)) and theta2(theta1(l)) = theta1(r|p). Hence, the term theta1(l) = ap(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),nil)) 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! ## Searching for a loop by unfolding (unfolding of variable subterms: ON)... # Iteration 0: no loop detected, 5 unfolded rules generated. # Iteration 1: no loop detected, 39 unfolded rules generated. # Iteration 2: loop detected, 126 unfolded rules generated. Here is the successful unfolding. Let IR be the TRS under analysis. L0 = ap^#(ap(ap(foldr,_0),_1),ap(ap(cons,_2),_3)) -> ap^#(ap(_0,_2),ap(ap(ap(foldr,_0),_1),_3)) is in U_IR^0. Let p0 = [0]. We unfold the rule of L0 forwards at position p0 with the rule ap(ap(f,_0),_0) -> ap(ap(_0,ap(f,_0)),ap(ap(cons,_0),nil)). ==> L1 = ap^#(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),_0)) -> ap^#(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),_0)) is in U_IR^1. Let p1 = [1]. We unfold the rule of L1 forwards at position p1 with the rule ap(ap(ap(foldr,_0),_1),nil) -> _1. ==> L2 = ap^#(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),nil)) -> ap^#(ap(ap(foldr,ap(f,foldr)),ap(ap(cons,foldr),nil)),ap(ap(cons,foldr),nil)) is in U_IR^2. ** END proof description ** Proof stopped at iteration 2 Number of unfolded rules generated by this proof = 170 Number of unfolded rules generated by all the parallel proofs = 170