/export/starexec/sandbox2/solver/bin/starexec_run_standard /export/starexec/sandbox2/benchmark/theBenchmark.xml /export/starexec/sandbox2/output/output_files -------------------------------------------------------------------------------- MAYBE proof of /export/starexec/sandbox2/benchmark/theBenchmark.xml # AProVE Commit ID: 48fb2092695e11cc9f56e44b17a92a5f88ffb256 marcel 20180622 unpublished dirty Outermost Termination of the given OTRS could not be shown: (0) OTRS (1) Thiemann-SpecialC-Transformation [EQUIVALENT, 0 ms] (2) QTRS (3) DependencyPairsProof [EQUIVALENT, 0 ms] (4) QDP (5) DependencyGraphProof [EQUIVALENT, 0 ms] (6) AND (7) QDP (8) UsableRulesProof [EQUIVALENT, 0 ms] (9) QDP (10) QReductionProof [EQUIVALENT, 0 ms] (11) QDP (12) UsableRulesReductionPairsProof [EQUIVALENT, 3 ms] (13) QDP (14) DependencyGraphProof [EQUIVALENT, 0 ms] (15) TRUE (16) QDP (17) UsableRulesProof [EQUIVALENT, 0 ms] (18) QDP (19) QReductionProof [EQUIVALENT, 0 ms] (20) QDP (21) TransformationProof [EQUIVALENT, 0 ms] (22) QDP (23) TransformationProof [EQUIVALENT, 0 ms] (24) QDP (25) TransformationProof [EQUIVALENT, 0 ms] (26) QDP (27) QDPOrderProof [EQUIVALENT, 21 ms] (28) QDP (29) UsableRulesProof [EQUIVALENT, 0 ms] (30) QDP (31) QReductionProof [EQUIVALENT, 0 ms] (32) QDP (33) Trivial-Transformation [SOUND, 0 ms] (34) QTRS (35) DependencyPairsProof [EQUIVALENT, 0 ms] (36) QDP (37) DependencyGraphProof [EQUIVALENT, 0 ms] (38) QDP (39) UsableRulesProof [EQUIVALENT, 0 ms] (40) QDP (41) TransformationProof [EQUIVALENT, 0 ms] (42) QDP (43) TransformationProof [EQUIVALENT, 0 ms] (44) QDP (45) NonTerminationLoopProof [COMPLETE, 0 ms] (46) NO ---------------------------------------- (0) Obligation: Term rewrite system R: The TRS R consists of the following rules: cons(x, cons(y, z)) -> big inf(x) -> cons(x, inf(s(x))) g(x, x) -> b Outermost Strategy. ---------------------------------------- (1) Thiemann-SpecialC-Transformation (EQUIVALENT) We applied the Thiemann-SpecialC transformation to transform the outermost TRS to an innermost TRS. ---------------------------------------- (2) Obligation: Q restricted rewrite system: The TRS R consists of the following rules: top(go_up(x)) -> top(reduce(x)) reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) redex_cons(x, cons(y, z)) -> result_cons(big) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) redex_g(x, x) -> result_g(b) check_cons(result_cons(x)) -> go_up(x) check_inf(result_inf(x)) -> go_up(x) check_g(result_g(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) check_inf(redex_inf(x_1)) -> in_inf_1(reduce(x_1)) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_inf_1(go_up(x_1)) -> go_up(inf(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) ---------------------------------------- (3) DependencyPairsProof (EQUIVALENT) Using Dependency Pairs [AG00,LPAR04] we result in the following initial DP problem. ---------------------------------------- (4) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(x)) -> TOP(reduce(x)) TOP(go_up(x)) -> REDUCE(x) REDUCE(cons(x_1, x_2)) -> CHECK_CONS(redex_cons(x_1, x_2)) REDUCE(cons(x_1, x_2)) -> REDEX_CONS(x_1, x_2) REDUCE(inf(x_1)) -> CHECK_INF(redex_inf(x_1)) REDUCE(inf(x_1)) -> REDEX_INF(x_1) REDUCE(g(x_1, x_2)) -> CHECK_G(redex_g(x_1, x_2)) REDUCE(g(x_1, x_2)) -> REDEX_G(x_1, x_2) CHECK_CONS(redex_cons(x_1, x_2)) -> IN_CONS_1(reduce(x_1), x_2) CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_1) CHECK_CONS(redex_cons(x_1, x_2)) -> IN_CONS_2(x_1, reduce(x_2)) CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_2) CHECK_INF(redex_inf(x_1)) -> IN_INF_1(reduce(x_1)) CHECK_INF(redex_inf(x_1)) -> REDUCE(x_1) CHECK_G(redex_g(x_1, x_2)) -> IN_G_1(reduce(x_1), x_2) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_1) CHECK_G(redex_g(x_1, x_2)) -> IN_G_2(x_1, reduce(x_2)) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_2) REDUCE(s(x_1)) -> IN_S_1(reduce(x_1)) REDUCE(s(x_1)) -> REDUCE(x_1) The TRS R consists of the following rules: top(go_up(x)) -> top(reduce(x)) reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) redex_cons(x, cons(y, z)) -> result_cons(big) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) redex_g(x, x) -> result_g(b) check_cons(result_cons(x)) -> go_up(x) check_inf(result_inf(x)) -> go_up(x) check_g(result_g(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) check_inf(redex_inf(x_1)) -> in_inf_1(reduce(x_1)) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_inf_1(go_up(x_1)) -> go_up(inf(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (5) DependencyGraphProof (EQUIVALENT) The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 2 SCCs with 12 less nodes. ---------------------------------------- (6) Complex Obligation (AND) ---------------------------------------- (7) Obligation: Q DP problem: The TRS P consists of the following rules: CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_1) REDUCE(cons(x_1, x_2)) -> CHECK_CONS(redex_cons(x_1, x_2)) CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_2) REDUCE(g(x_1, x_2)) -> CHECK_G(redex_g(x_1, x_2)) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_1) REDUCE(s(x_1)) -> REDUCE(x_1) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_2) The TRS R consists of the following rules: top(go_up(x)) -> top(reduce(x)) reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) redex_cons(x, cons(y, z)) -> result_cons(big) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) redex_g(x, x) -> result_g(b) check_cons(result_cons(x)) -> go_up(x) check_inf(result_inf(x)) -> go_up(x) check_g(result_g(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) check_inf(redex_inf(x_1)) -> in_inf_1(reduce(x_1)) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_inf_1(go_up(x_1)) -> go_up(inf(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (8) UsableRulesProof (EQUIVALENT) As all Q-normal forms are R-normal forms we are in the innermost case. Hence, by the usable rules processor [LPAR04] we can delete all non-usable rules [FROCOS05] from R. ---------------------------------------- (9) Obligation: Q DP problem: The TRS P consists of the following rules: CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_1) REDUCE(cons(x_1, x_2)) -> CHECK_CONS(redex_cons(x_1, x_2)) CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_2) REDUCE(g(x_1, x_2)) -> CHECK_G(redex_g(x_1, x_2)) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_1) REDUCE(s(x_1)) -> REDUCE(x_1) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_2) The TRS R consists of the following rules: redex_g(x, x) -> result_g(b) redex_cons(x, cons(y, z)) -> result_cons(big) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (10) QReductionProof (EQUIVALENT) We deleted the following terms from Q as each root-symbol of these terms does neither occur in P nor in R.[THIEMANN]. top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_inf(x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) ---------------------------------------- (11) Obligation: Q DP problem: The TRS P consists of the following rules: CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_1) REDUCE(cons(x_1, x_2)) -> CHECK_CONS(redex_cons(x_1, x_2)) CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_2) REDUCE(g(x_1, x_2)) -> CHECK_G(redex_g(x_1, x_2)) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_1) REDUCE(s(x_1)) -> REDUCE(x_1) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_2) The TRS R consists of the following rules: redex_g(x, x) -> result_g(b) redex_cons(x, cons(y, z)) -> result_cons(big) The set Q consists of the following terms: redex_cons(x0, cons(x1, x2)) redex_g(x0, x0) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (12) UsableRulesReductionPairsProof (EQUIVALENT) By using the usable rules with reduction pair processor [LPAR04] with a polynomial ordering [POLO], all dependency pairs and the corresponding usable rules [FROCOS05] can be oriented non-strictly. All non-usable rules are removed, and those dependency pairs and usable rules that have been oriented strictly or contain non-usable symbols in their left-hand side are removed as well. The following dependency pairs can be deleted: REDUCE(cons(x_1, x_2)) -> CHECK_CONS(redex_cons(x_1, x_2)) REDUCE(g(x_1, x_2)) -> CHECK_G(redex_g(x_1, x_2)) REDUCE(s(x_1)) -> REDUCE(x_1) The following rules are removed from R: redex_cons(x, cons(y, z)) -> result_cons(big) Used ordering: POLO with Polynomial interpretation [POLO]: POL(CHECK_CONS(x_1)) = x_1 POL(CHECK_G(x_1)) = 2*x_1 POL(REDUCE(x_1)) = 2*x_1 POL(b) = 0 POL(big) = 0 POL(cons(x_1, x_2)) = 2*x_1 + 2*x_2 POL(g(x_1, x_2)) = 2*x_1 + 2*x_2 POL(redex_cons(x_1, x_2)) = 2*x_1 + 2*x_2 POL(redex_g(x_1, x_2)) = x_1 + x_2 POL(result_cons(x_1)) = x_1 POL(result_g(x_1)) = x_1 POL(s(x_1)) = 2*x_1 ---------------------------------------- (13) Obligation: Q DP problem: The TRS P consists of the following rules: CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_1) CHECK_CONS(redex_cons(x_1, x_2)) -> REDUCE(x_2) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_1) CHECK_G(redex_g(x_1, x_2)) -> REDUCE(x_2) The TRS R consists of the following rules: redex_g(x, x) -> result_g(b) The set Q consists of the following terms: redex_cons(x0, cons(x1, x2)) redex_g(x0, x0) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (14) DependencyGraphProof (EQUIVALENT) The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 0 SCCs with 4 less nodes. ---------------------------------------- (15) TRUE ---------------------------------------- (16) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(x)) -> TOP(reduce(x)) The TRS R consists of the following rules: top(go_up(x)) -> top(reduce(x)) reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) redex_cons(x, cons(y, z)) -> result_cons(big) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) redex_g(x, x) -> result_g(b) check_cons(result_cons(x)) -> go_up(x) check_inf(result_inf(x)) -> go_up(x) check_g(result_g(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) check_inf(redex_inf(x_1)) -> in_inf_1(reduce(x_1)) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_inf_1(go_up(x_1)) -> go_up(inf(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (17) UsableRulesProof (EQUIVALENT) As all Q-normal forms are R-normal forms we are in the innermost case. Hence, by the usable rules processor [LPAR04] we can delete all non-usable rules [FROCOS05] from R. ---------------------------------------- (18) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(x)) -> TOP(reduce(x)) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (19) QReductionProof (EQUIVALENT) We deleted the following terms from Q as each root-symbol of these terms does neither occur in P nor in R.[THIEMANN]. top(go_up(x0)) in_inf_1(go_up(x0)) ---------------------------------------- (20) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(x)) -> TOP(reduce(x)) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (21) TransformationProof (EQUIVALENT) By narrowing [LPAR04] the rule TOP(go_up(x)) -> TOP(reduce(x)) at position [0] we obtained the following new rules [LPAR04]: (TOP(go_up(cons(x0, x1))) -> TOP(check_cons(redex_cons(x0, x1))),TOP(go_up(cons(x0, x1))) -> TOP(check_cons(redex_cons(x0, x1)))) (TOP(go_up(inf(x0))) -> TOP(check_inf(redex_inf(x0))),TOP(go_up(inf(x0))) -> TOP(check_inf(redex_inf(x0)))) (TOP(go_up(g(x0, x1))) -> TOP(check_g(redex_g(x0, x1))),TOP(go_up(g(x0, x1))) -> TOP(check_g(redex_g(x0, x1)))) (TOP(go_up(s(x0))) -> TOP(in_s_1(reduce(x0))),TOP(go_up(s(x0))) -> TOP(in_s_1(reduce(x0)))) ---------------------------------------- (22) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(cons(x0, x1))) -> TOP(check_cons(redex_cons(x0, x1))) TOP(go_up(inf(x0))) -> TOP(check_inf(redex_inf(x0))) TOP(go_up(g(x0, x1))) -> TOP(check_g(redex_g(x0, x1))) TOP(go_up(s(x0))) -> TOP(in_s_1(reduce(x0))) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (23) TransformationProof (EQUIVALENT) By rewriting [LPAR04] the rule TOP(go_up(inf(x0))) -> TOP(check_inf(redex_inf(x0))) at position [0,0] we obtained the following new rules [LPAR04]: (TOP(go_up(inf(x0))) -> TOP(check_inf(result_inf(cons(x0, inf(s(x0)))))),TOP(go_up(inf(x0))) -> TOP(check_inf(result_inf(cons(x0, inf(s(x0))))))) ---------------------------------------- (24) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(cons(x0, x1))) -> TOP(check_cons(redex_cons(x0, x1))) TOP(go_up(g(x0, x1))) -> TOP(check_g(redex_g(x0, x1))) TOP(go_up(s(x0))) -> TOP(in_s_1(reduce(x0))) TOP(go_up(inf(x0))) -> TOP(check_inf(result_inf(cons(x0, inf(s(x0)))))) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (25) TransformationProof (EQUIVALENT) By rewriting [LPAR04] the rule TOP(go_up(inf(x0))) -> TOP(check_inf(result_inf(cons(x0, inf(s(x0)))))) at position [0] we obtained the following new rules [LPAR04]: (TOP(go_up(inf(x0))) -> TOP(go_up(cons(x0, inf(s(x0))))),TOP(go_up(inf(x0))) -> TOP(go_up(cons(x0, inf(s(x0)))))) ---------------------------------------- (26) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(cons(x0, x1))) -> TOP(check_cons(redex_cons(x0, x1))) TOP(go_up(g(x0, x1))) -> TOP(check_g(redex_g(x0, x1))) TOP(go_up(s(x0))) -> TOP(in_s_1(reduce(x0))) TOP(go_up(inf(x0))) -> TOP(go_up(cons(x0, inf(s(x0))))) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (27) QDPOrderProof (EQUIVALENT) We use the reduction pair processor [LPAR04,JAR06]. The following pairs can be oriented strictly and are deleted. TOP(go_up(inf(x0))) -> TOP(go_up(cons(x0, inf(s(x0))))) The remaining pairs can at least be oriented weakly. Used ordering: Polynomial interpretation [POLO]: POL(TOP(x_1)) = x_1 POL(b) = 0 POL(big) = 0 POL(check_cons(x_1)) = x_1 POL(check_g(x_1)) = x_1 POL(check_inf(x_1)) = 1 POL(cons(x_1, x_2)) = 0 POL(g(x_1, x_2)) = 0 POL(go_up(x_1)) = x_1 POL(in_cons_1(x_1, x_2)) = 0 POL(in_cons_2(x_1, x_2)) = 0 POL(in_g_1(x_1, x_2)) = 0 POL(in_g_2(x_1, x_2)) = 0 POL(in_s_1(x_1)) = 0 POL(inf(x_1)) = 1 POL(redex_cons(x_1, x_2)) = 0 POL(redex_g(x_1, x_2)) = 0 POL(redex_inf(x_1)) = x_1 POL(reduce(x_1)) = 0 POL(result_cons(x_1)) = x_1 POL(result_g(x_1)) = x_1 POL(result_inf(x_1)) = 1 POL(s(x_1)) = 0 The following usable rules [FROCOS05] with respect to the argument filtering of the ordering [JAR06] were oriented: redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) ---------------------------------------- (28) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(cons(x0, x1))) -> TOP(check_cons(redex_cons(x0, x1))) TOP(go_up(g(x0, x1))) -> TOP(check_g(redex_g(x0, x1))) TOP(go_up(s(x0))) -> TOP(in_s_1(reduce(x0))) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (29) UsableRulesProof (EQUIVALENT) As all Q-normal forms are R-normal forms we are in the innermost case. Hence, by the usable rules processor [LPAR04] we can delete all non-usable rules [FROCOS05] from R. ---------------------------------------- (30) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(x)) -> TOP(reduce(x)) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: top(go_up(x0)) reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_inf_1(go_up(x0)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (31) QReductionProof (EQUIVALENT) We deleted the following terms from Q as each root-symbol of these terms does neither occur in P nor in R.[THIEMANN]. top(go_up(x0)) in_inf_1(go_up(x0)) ---------------------------------------- (32) Obligation: Q DP problem: The TRS P consists of the following rules: TOP(go_up(x)) -> TOP(reduce(x)) The TRS R consists of the following rules: reduce(cons(x_1, x_2)) -> check_cons(redex_cons(x_1, x_2)) reduce(inf(x_1)) -> check_inf(redex_inf(x_1)) reduce(g(x_1, x_2)) -> check_g(redex_g(x_1, x_2)) reduce(s(x_1)) -> in_s_1(reduce(x_1)) in_s_1(go_up(x_1)) -> go_up(s(x_1)) redex_g(x, x) -> result_g(b) check_g(result_g(x)) -> go_up(x) check_g(redex_g(x_1, x_2)) -> in_g_1(reduce(x_1), x_2) check_g(redex_g(x_1, x_2)) -> in_g_2(x_1, reduce(x_2)) in_g_2(x_1, go_up(x_2)) -> go_up(g(x_1, x_2)) in_g_1(go_up(x_1), x_2) -> go_up(g(x_1, x_2)) redex_inf(x) -> result_inf(cons(x, inf(s(x)))) check_inf(result_inf(x)) -> go_up(x) redex_cons(x, cons(y, z)) -> result_cons(big) check_cons(result_cons(x)) -> go_up(x) check_cons(redex_cons(x_1, x_2)) -> in_cons_1(reduce(x_1), x_2) check_cons(redex_cons(x_1, x_2)) -> in_cons_2(x_1, reduce(x_2)) in_cons_2(x_1, go_up(x_2)) -> go_up(cons(x_1, x_2)) in_cons_1(go_up(x_1), x_2) -> go_up(cons(x_1, x_2)) The set Q consists of the following terms: reduce(cons(x0, x1)) reduce(inf(x0)) reduce(g(x0, x1)) redex_cons(x0, cons(x1, x2)) redex_inf(x0) redex_g(x0, x0) check_cons(result_cons(x0)) check_inf(result_inf(x0)) check_g(result_g(x0)) check_cons(redex_cons(x0, x1)) check_g(redex_g(x0, x1)) reduce(s(x0)) in_cons_1(go_up(x0), x1) in_cons_2(x0, go_up(x1)) in_s_1(go_up(x0)) in_g_1(go_up(x0), x1) in_g_2(x0, go_up(x1)) We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (33) Trivial-Transformation (SOUND) We applied the Trivial transformation to transform the outermost TRS to a standard TRS. ---------------------------------------- (34) Obligation: Q restricted rewrite system: The TRS R consists of the following rules: cons(x, cons(y, z)) -> big inf(x) -> cons(x, inf(s(x))) g(x, x) -> b Q is empty. ---------------------------------------- (35) DependencyPairsProof (EQUIVALENT) Using Dependency Pairs [AG00,LPAR04] we result in the following initial DP problem. ---------------------------------------- (36) Obligation: Q DP problem: The TRS P consists of the following rules: INF(x) -> CONS(x, inf(s(x))) INF(x) -> INF(s(x)) The TRS R consists of the following rules: cons(x, cons(y, z)) -> big inf(x) -> cons(x, inf(s(x))) g(x, x) -> b Q is empty. We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (37) DependencyGraphProof (EQUIVALENT) The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 1 SCC with 1 less node. ---------------------------------------- (38) Obligation: Q DP problem: The TRS P consists of the following rules: INF(x) -> INF(s(x)) The TRS R consists of the following rules: cons(x, cons(y, z)) -> big inf(x) -> cons(x, inf(s(x))) g(x, x) -> b Q is empty. We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (39) UsableRulesProof (EQUIVALENT) We can use the usable rules and reduction pair processor [LPAR04] with the Ce-compatible extension of the polynomial order that maps every function symbol to the sum of its arguments. Then, we can delete all non-usable rules [FROCOS05] from R. ---------------------------------------- (40) Obligation: Q DP problem: The TRS P consists of the following rules: INF(x) -> INF(s(x)) R is empty. Q is empty. We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (41) TransformationProof (EQUIVALENT) By instantiating [LPAR04] the rule INF(x) -> INF(s(x)) we obtained the following new rules [LPAR04]: (INF(s(z0)) -> INF(s(s(z0))),INF(s(z0)) -> INF(s(s(z0)))) ---------------------------------------- (42) Obligation: Q DP problem: The TRS P consists of the following rules: INF(s(z0)) -> INF(s(s(z0))) R is empty. Q is empty. We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (43) TransformationProof (EQUIVALENT) By instantiating [LPAR04] the rule INF(s(z0)) -> INF(s(s(z0))) we obtained the following new rules [LPAR04]: (INF(s(s(z0))) -> INF(s(s(s(z0)))),INF(s(s(z0))) -> INF(s(s(s(z0))))) ---------------------------------------- (44) Obligation: Q DP problem: The TRS P consists of the following rules: INF(s(s(z0))) -> INF(s(s(s(z0)))) R is empty. Q is empty. We have to consider all minimal (P,Q,R)-chains. ---------------------------------------- (45) NonTerminationLoopProof (COMPLETE) We used the non-termination processor [FROCOS05] to show that the DP problem is infinite. Found a loop by semiunifying a rule from P directly. s = INF(s(s(z0))) evaluates to t =INF(s(s(s(z0)))) Thus s starts an infinite chain as s semiunifies with t with the following substitutions: * Matcher: [z0 / s(z0)] * Semiunifier: [ ] -------------------------------------------------------------------------------- Rewriting sequence The DP semiunifies directly so there is only one rewrite step from INF(s(s(z0))) to INF(s(s(s(z0)))). ---------------------------------------- (46) NO