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. lexicographic path order with precedence: precedence: cons > a__f# > f > a__f > mark > mark# > a__p# > p > a__p > |0| > s argument filter: pi(a__f#) = 1 pi(s) = [1] pi(|0|) = [] pi(a__p) = 1 pi(a__p#) = 1 pi(mark#) = 1 pi(cons) = 1 pi(p) = 1 pi(mark) = 1 pi(f) = 1 pi(a__f) = 1 2. lexicographic path order with precedence: precedence: cons > mark > a__f > a__p > f > mark# > a__f# > a__p# > p > |0| > s argument filter: pi(a__f#) = [] pi(s) = [] pi(|0|) = [] pi(a__p) = [1] pi(a__p#) = [] pi(mark#) = [] pi(cons) = 1 pi(p) = [1] pi(mark) = [1] pi(f) = [] pi(a__f) = [] 3. lexicographic path order with precedence: precedence: a__p > a__f# > f > a__f > |0| > cons > mark > a__p# > mark# > p > s argument filter: pi(a__f#) = [] pi(s) = [] pi(|0|) = [] pi(a__p) = 1 pi(a__p#) = [] pi(mark#) = [] pi(cons) = [1] pi(p) = [1] pi(mark) = 1 pi(f) = [] pi(a__f) = [] The next rules are strictly ordered: p2, p3, p4, p7, 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: mark#(cons(X1,X2)) -> mark#(X1) p3: mark#(p(X)) -> mark#(X) p4: mark#(f(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} -- 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. lexicographic path order with precedence: precedence: f > cons > s > mark > a__p > p > |0| > a__f > a__f# argument filter: pi(a__f#) = [1] pi(s) = 1 pi(|0|) = [] pi(a__p) = 1 pi(a__f) = 1 pi(cons) = 1 pi(f) = 1 pi(mark) = 1 pi(p) = 1 2. lexicographic path order with precedence: precedence: cons > |0| > a__f# > f > s > a__f > p > a__p > mark argument filter: pi(a__f#) = [1] pi(s) = [1] pi(|0|) = [] pi(a__p) = 1 pi(a__f) = 1 pi(cons) = 1 pi(f) = 1 pi(mark) = 1 pi(p) = 1 3. lexicographic path order with precedence: precedence: mark > a__f# > s > f > a__p > |0| > a__f > cons > p argument filter: pi(a__f#) = 1 pi(s) = [1] pi(|0|) = [] pi(a__p) = [] pi(a__f) = 1 pi(cons) = [] pi(f) = 1 pi(mark) = [1] pi(p) = [] 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: mark#(cons(X1,X2)) -> mark#(X1) p2: mark#(f(X)) -> mark#(X) p3: mark#(p(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 set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: p > f > mark# > cons argument filter: pi(mark#) = 1 pi(cons) = [1, 2] pi(f) = [1] pi(p) = [1] 2. lexicographic path order with precedence: precedence: mark# > p > f > cons argument filter: pi(mark#) = [] pi(cons) = [1, 2] pi(f) = [] pi(p) = [] 3. lexicographic path order with precedence: precedence: mark# > p > f > cons argument filter: pi(mark#) = [] pi(cons) = [1, 2] pi(f) = [] pi(p) = [] The next rules are strictly ordered: p1, p2, p3 We remove them from the problem. Then no dependency pair remains.