NO Prover = TRS(tech=PATTERN_RULES, nb_unfoldings=unlimited, max_nb_unfolded_rules=200) ** BEGIN proof argument ** The following pattern rule was generated by the strategy presented in Sect. 3 of [Emmes, Enger, Giesl, IJCAR'12]: [iteration = 4] f(tt,s(s(_0))){_0->s(_0)}^n{_0->0} -> f(tt,s(s(s(_0)))){_0->s(_0)}^n{_0->0} We apply Theorem 8 of [Emmes, Enger, Giesl, IJCAR'12] on this rule with m = 1, b = 1, pi = epsilon, sigma' = {} and mu' = {}. Hence the term f(tt,s(s(0))), obtained from instantiating n with 0 in the left-hand side of the rule, starts an infinite derivation 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^#(tt,_0) -> f^#(eq(toOne(_0),s(0)),s(_0))] TRS = {f(tt,_0) -> f(eq(toOne(_0),s(0)),s(_0)), eq(s(_0),s(_1)) -> eq(_0,_1), eq(0,0) -> tt, toOne(s(s(_0))) -> toOne(s(_0)), toOne(s(0)) -> s(0)} ## Trying with homeomorphic embeddings... Failed! ## Trying with polynomial interpretations... Too many coefficients (15)! Aborting! ## Trying with lexicographic path orders... Failed! ## Trying to prove nontermination by unfolding the dependency pairs with the rules of the TRS # Iteration 0: nontermination not detected, 1 unfolded rule generated. # Iteration 1: nontermination not detected, 5 unfolded rules generated. # Iteration 2: nontermination not detected, 16 unfolded rules generated. # Iteration 3: nontermination not detected, 43 unfolded rules generated. # Iteration 4: nontermination detected, 98 unfolded rules generated. Here is the successful unfolding. Let IR be the TRS under analysis. IR contains the dependency pair f^#(tt,_0) -> f^#(eq(toOne(_0),s(0)),s(_0)). We apply (I) of [Emmes, Enger, Giesl, IJCAR'12] to this dependency pair. ==> P0 = f^#(tt,_0){}^n{} -> f^#(eq(toOne(_0),s(0)),s(_0)){}^n{} is in U_IR^0. We apply (VI) of [Emmes, Enger, Giesl, IJCAR'12] to this pattern rule at position [0, 0] using the pattern rule toOne(s(s(_0))){_0->s(_0)}^n{_0->_1} -> toOne(s(_1)){_0->s(_0)}^n{_0->_1} obtained from IR. ==> P1 = f^#(tt,s(s(_0))){_0->s(_0)}^n{_0->_1} -> f^#(eq(toOne(s(_1)),s(0)),s(s(s(_0)))){_0->s(_0)}^n{_0->_1} is in U_IR^1. We apply (V) + (IX) of [Emmes, Enger, Giesl, IJCAR'12] to this pattern rule at position [0, 0] using the rule toOne(s(0)) -> s(0) of IR. ==> P2 = f^#(tt,s(s(_0))){_0->s(_0)}^n{_0->0} -> f^#(eq(s(0),s(0)),s(s(s(_0)))){_0->s(_0)}^n{_0->0} is in U_IR^2. We apply (IX) of [Emmes, Enger, Giesl, IJCAR'12] to this pattern rule at position [0] using the rule eq(s(_0),s(_1)) -> eq(_0,_1) of IR. ==> P3 = f^#(tt,s(s(_0))){_0->s(_0)}^n{_0->0} -> f^#(eq(0,0),s(s(s(_0)))){_0->s(_0)}^n{_0->0} is in U_IR^3. We apply (IX) of [Emmes, Enger, Giesl, IJCAR'12] to this pattern rule at position [0] using the rule eq(0,0) -> tt of IR. ==> P4 = f^#(tt,s(s(_0))){_0->s(_0)}^n{_0->0} -> f^#(tt,s(s(s(_0)))){_0->s(_0)}^n{_0->0} is in U_IR^4. This DP problem is infinite. ** END proof description ** Proof stopped at iteration 4 Number of unfolded rules generated by this proof = 163 Number of unfolded rules generated by all the parallel proofs = 689