YES We show the termination of the TRS R: a__f(|0|()) -> cons(|0|(),f(s(|0|()))) a__f(s(|0|())) -> a__f(a__p(s(|0|()))) a__p(s(X)) -> mark(X) mark(f(X)) -> a__f(mark(X)) mark(p(X)) -> a__p(mark(X)) mark(|0|()) -> |0|() mark(cons(X1,X2)) -> cons(mark(X1),X2) mark(s(X)) -> s(mark(X)) a__f(X) -> f(X) a__p(X) -> p(X) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a__f#(s(|0|())) -> a__f#(a__p(s(|0|()))) p2: a__f#(s(|0|())) -> a__p#(s(|0|())) p3: a__p#(s(X)) -> mark#(X) p4: mark#(f(X)) -> a__f#(mark(X)) p5: mark#(f(X)) -> mark#(X) p6: mark#(p(X)) -> a__p#(mark(X)) p7: mark#(p(X)) -> mark#(X) p8: mark#(cons(X1,X2)) -> mark#(X1) p9: mark#(s(X)) -> mark#(X) and R consists of: r1: a__f(|0|()) -> cons(|0|(),f(s(|0|()))) r2: a__f(s(|0|())) -> a__f(a__p(s(|0|()))) r3: a__p(s(X)) -> mark(X) r4: mark(f(X)) -> a__f(mark(X)) r5: mark(p(X)) -> a__p(mark(X)) r6: mark(|0|()) -> |0|() r7: mark(cons(X1,X2)) -> cons(mark(X1),X2) r8: mark(s(X)) -> s(mark(X)) r9: a__f(X) -> f(X) r10: a__p(X) -> p(X) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5, p6, p7, p8, p9} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a__f#(s(|0|())) -> a__f#(a__p(s(|0|()))) p2: a__f#(s(|0|())) -> a__p#(s(|0|())) p3: a__p#(s(X)) -> mark#(X) p4: mark#(s(X)) -> mark#(X) p5: mark#(cons(X1,X2)) -> mark#(X1) p6: mark#(p(X)) -> mark#(X) p7: mark#(p(X)) -> a__p#(mark(X)) p8: mark#(f(X)) -> mark#(X) p9: mark#(f(X)) -> a__f#(mark(X)) and R consists of: r1: a__f(|0|()) -> cons(|0|(),f(s(|0|()))) r2: a__f(s(|0|())) -> a__f(a__p(s(|0|()))) r3: a__p(s(X)) -> mark(X) r4: mark(f(X)) -> a__f(mark(X)) r5: mark(p(X)) -> a__p(mark(X)) r6: mark(|0|()) -> |0|() r7: mark(cons(X1,X2)) -> cons(mark(X1),X2) r8: mark(s(X)) -> s(mark(X)) r9: a__f(X) -> f(X) r10: a__p(X) -> p(X) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: a__f#_A(x1) = max{14, x1 - 4} s_A(x1) = x1 + 7 |0|_A = 4 a__p_A(x1) = x1 + 7 a__p#_A(x1) = max{6, x1 - 8} mark#_A(x1) = max{0, x1 - 1} cons_A(x1,x2) = max{5, x1 + 2, x2 - 8} p_A(x1) = x1 + 7 mark_A(x1) = x1 + 14 f_A(x1) = max{21, x1 + 16} a__f_A(x1) = max{35, x1 + 16} 2. max/plus interpretations on natural numbers: a__f#_A(x1) = 0 s_A(x1) = x1 + 17 |0|_A = 2 a__p_A(x1) = max{8, x1 + 6} a__p#_A(x1) = 11 mark#_A(x1) = 11 cons_A(x1,x2) = 32 p_A(x1) = max{7, x1 + 6} mark_A(x1) = x1 + 22 f_A(x1) = 10 a__f_A(x1) = 31 The next rules are strictly ordered: p2, p4, p5, p6, p8, p9 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a__f#(s(|0|())) -> a__f#(a__p(s(|0|()))) p2: a__p#(s(X)) -> mark#(X) p3: mark#(p(X)) -> a__p#(mark(X)) and R consists of: r1: a__f(|0|()) -> cons(|0|(),f(s(|0|()))) r2: a__f(s(|0|())) -> a__f(a__p(s(|0|()))) r3: a__p(s(X)) -> mark(X) r4: mark(f(X)) -> a__f(mark(X)) r5: mark(p(X)) -> a__p(mark(X)) r6: mark(|0|()) -> |0|() r7: mark(cons(X1,X2)) -> cons(mark(X1),X2) r8: mark(s(X)) -> s(mark(X)) r9: a__f(X) -> f(X) r10: a__p(X) -> p(X) The estimated dependency graph contains the following SCCs: {p1} {p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a__f#(s(|0|())) -> a__f#(a__p(s(|0|()))) and R consists of: r1: a__f(|0|()) -> cons(|0|(),f(s(|0|()))) r2: a__f(s(|0|())) -> a__f(a__p(s(|0|()))) r3: a__p(s(X)) -> mark(X) r4: mark(f(X)) -> a__f(mark(X)) r5: mark(p(X)) -> a__p(mark(X)) r6: mark(|0|()) -> |0|() r7: mark(cons(X1,X2)) -> cons(mark(X1),X2) r8: mark(s(X)) -> s(mark(X)) r9: a__f(X) -> f(X) r10: a__p(X) -> p(X) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: a__f#_A(x1) = max{0, x1 - 18} s_A(x1) = x1 + 19 |0|_A = 5 a__p_A(x1) = max{3, x1 - 7} a__f_A(x1) = max{3, x1 + 1} cons_A(x1,x2) = max{4, x1 + 1} f_A(x1) = max{2, x1 + 1} mark_A(x1) = x1 + 11 p_A(x1) = max{0, x1 - 7} 2. max/plus interpretations on natural numbers: a__f#_A(x1) = 0 s_A(x1) = max{4, x1 - 1} |0|_A = 5 a__p_A(x1) = 1 a__f_A(x1) = 2 cons_A(x1,x2) = 0 f_A(x1) = 0 mark_A(x1) = x1 + 4 p_A(x1) = 0 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a__p#(s(X)) -> mark#(X) p2: mark#(p(X)) -> a__p#(mark(X)) and R consists of: r1: a__f(|0|()) -> cons(|0|(),f(s(|0|()))) r2: a__f(s(|0|())) -> a__f(a__p(s(|0|()))) r3: a__p(s(X)) -> mark(X) r4: mark(f(X)) -> a__f(mark(X)) r5: mark(p(X)) -> a__p(mark(X)) r6: mark(|0|()) -> |0|() r7: mark(cons(X1,X2)) -> cons(mark(X1),X2) r8: mark(s(X)) -> s(mark(X)) r9: a__f(X) -> f(X) r10: a__p(X) -> p(X) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: a__p#_A(x1) = x1 s_A(x1) = x1 + 6 mark#_A(x1) = x1 + 6 p_A(x1) = x1 + 6 mark_A(x1) = x1 + 12 a__f_A(x1) = 10 |0|_A = 7 cons_A(x1,x2) = max{7, x1 + 2, x2 - 3} f_A(x1) = 10 a__p_A(x1) = x1 + 6 2. max/plus interpretations on natural numbers: a__p#_A(x1) = max{3, x1 + 1} s_A(x1) = x1 + 2 mark#_A(x1) = x1 + 2 p_A(x1) = max{4, x1} mark_A(x1) = x1 a__f_A(x1) = 4 |0|_A = 5 cons_A(x1,x2) = 5 f_A(x1) = 2 a__p_A(x1) = max{4, x1} The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.