YES We show the termination of the TRS R: app(app(plus(),|0|()),y) -> y app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) app(app(map(),f),nil()) -> nil() app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) Instead we prove termination of the uncurried system: app(cons_0(),y) -> cons_1(y) app(cons_1(x1),y) -> cons_2(x1,y) app(inc_0(),y) -> inc_1(y) app(map_0(),y) -> map_1(y) app(map_1(x1),y) -> map_2(x1,y) app(plus_0(),y) -> plus_1(y) app(plus_1(x1),y) -> plus_2(x1,y) app(s_0(),y) -> s_1(y) plus_2(|0|_0(),y) -> y plus_2(s_1(x),y) -> s_1(plus_2(x,y)) inc_1(xs) -> map_2(plus_1(s_1(|0|_0())),xs) map_2(f,nil_0()) -> nil_0() map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(inc_0(),y) -> inc_1#(y) p2: app#(map_1(x1),y) -> map_2#(x1,y) p3: app#(plus_1(x1),y) -> plus_2#(x1,y) p4: plus_2#(s_1(x),y) -> plus_2#(x,y) p5: inc_1#(xs) -> map_2#(plus_1(s_1(|0|_0())),xs) p6: map_2#(f,cons_2(x,xs)) -> app#(f,x) p7: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) and R consists of: r1: app(cons_0(),y) -> cons_1(y) r2: app(cons_1(x1),y) -> cons_2(x1,y) r3: app(inc_0(),y) -> inc_1(y) r4: app(map_0(),y) -> map_1(y) r5: app(map_1(x1),y) -> map_2(x1,y) r6: app(plus_0(),y) -> plus_1(y) r7: app(plus_1(x1),y) -> plus_2(x1,y) r8: app(s_0(),y) -> s_1(y) r9: plus_2(|0|_0(),y) -> y r10: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r11: inc_1(xs) -> map_2(plus_1(s_1(|0|_0())),xs) r12: map_2(f,nil_0()) -> nil_0() r13: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) The estimated dependency graph contains the following SCCs: {p1, p2, p5, p6, p7} {p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(inc_0(),y) -> inc_1#(y) p2: inc_1#(xs) -> map_2#(plus_1(s_1(|0|_0())),xs) p3: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p4: map_2#(f,cons_2(x,xs)) -> app#(f,x) p5: app#(map_1(x1),y) -> map_2#(x1,y) and R consists of: r1: app(cons_0(),y) -> cons_1(y) r2: app(cons_1(x1),y) -> cons_2(x1,y) r3: app(inc_0(),y) -> inc_1(y) r4: app(map_0(),y) -> map_1(y) r5: app(map_1(x1),y) -> map_2(x1,y) r6: app(plus_0(),y) -> plus_1(y) r7: app(plus_1(x1),y) -> plus_2(x1,y) r8: app(s_0(),y) -> s_1(y) r9: plus_2(|0|_0(),y) -> y r10: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r11: inc_1(xs) -> map_2(plus_1(s_1(|0|_0())),xs) r12: map_2(f,nil_0()) -> nil_0() r13: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: app#_A(x1,x2) = max{0, x1 - 17, x2 - 15} inc_0_A = 14 inc_1#_A(x1) = max{0, x1 - 15} map_2#_A(x1,x2) = max{0, x1 - 14, x2 - 23} plus_1_A(x1) = max{11, x1 + 2} s_1_A(x1) = max{11, x1 - 10} |0|_0_A = 8 cons_2_A(x1,x2) = max{x1 + 22, x2 + 22} map_1_A(x1) = x1 + 16 app#!_A(x1,x2) = max{5, x1 - 15, x2 - 1} inc_0!_A = 4 inc_1#!_A(x1) = max{5, x1 - 15} map_2#!_A(x1,x2) = max{4, x1 - 14, x2 - 16} plus_1!_A(x1) = max{3, x1 - 12} s_1!_A(x1) = max{6, x1 - 33} |0|_0!_A = 6 cons_2!_A(x1,x2) = max{1, x1 - 3, x2 - 24} map_1!_A(x1) = max{1, x1 - 37} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: app#_A(x1,x2) = max{0, x1 - 28, x2 - 20} inc_0_A = 27 inc_1#_A(x1) = max{0, x1 - 20} map_2#_A(x1,x2) = max{0, x1 - 26, x2 - 20} plus_1_A(x1) = x1 + 16 s_1_A(x1) = max{9, x1 - 9} |0|_0_A = 0 cons_2_A(x1,x2) = max{x1 + 13, x2 + 15} map_1_A(x1) = max{27, x1 + 2} app#!_A(x1,x2) = max{5, x1 - 30, x2 + 3} inc_0!_A = 5 inc_1#!_A(x1) = max{4, x1 - 25} map_2#!_A(x1,x2) = max{2, x1 - 29, x2 - 26} plus_1!_A(x1) = max{6, x1 - 35} s_1!_A(x1) = max{7, x1 - 24} |0|_0!_A = 7 cons_2!_A(x1,x2) = x1 + 1 map_1!_A(x1) = max{1, x1 - 29} partial status: pi(app#) = [1] pi(inc_0) = [] pi(inc_1#) = [] pi(map_2#) = [1] pi(plus_1) = [] pi(s_1) = [1] pi(|0|_0) = [] pi(cons_2) = [2] pi(map_1) = [1] The following rules are removed: p1, p2, p4, p5 -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) and R consists of: r1: app(cons_0(),y) -> cons_1(y) r2: app(cons_1(x1),y) -> cons_2(x1,y) r3: app(inc_0(),y) -> inc_1(y) r4: app(map_0(),y) -> map_1(y) r5: app(map_1(x1),y) -> map_2(x1,y) r6: app(plus_0(),y) -> plus_1(y) r7: app(plus_1(x1),y) -> plus_2(x1,y) r8: app(s_0(),y) -> s_1(y) r9: plus_2(|0|_0(),y) -> y r10: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r11: inc_1(xs) -> map_2(plus_1(s_1(|0|_0())),xs) r12: map_2(f,nil_0()) -> nil_0() r13: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) and R consists of: r1: app(cons_0(),y) -> cons_1(y) r2: app(cons_1(x1),y) -> cons_2(x1,y) r3: app(inc_0(),y) -> inc_1(y) r4: app(map_0(),y) -> map_1(y) r5: app(map_1(x1),y) -> map_2(x1,y) r6: app(plus_0(),y) -> plus_1(y) r7: app(plus_1(x1),y) -> plus_2(x1,y) r8: app(s_0(),y) -> s_1(y) r9: plus_2(|0|_0(),y) -> y r10: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r11: inc_1(xs) -> map_2(plus_1(s_1(|0|_0())),xs) r12: map_2(f,nil_0()) -> nil_0() r13: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: map_2#_A(x1,x2) = 0 cons_2_A(x1,x2) = max{13, x1 - 2, x2 - 4} map_2#!_A(x1,x2) = max{0, x2 - 14} cons_2!_A(x1,x2) = max{2, x1 - 3, x2 - 13} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: map_2#_A(x1,x2) = 0 cons_2_A(x1,x2) = max{4, x1 - 2, x2 - 4} map_2#!_A(x1,x2) = max{1, x1 - 1, x2 - 5} cons_2!_A(x1,x2) = max{0, x1 - 11} partial status: pi(map_2#) = [2] pi(cons_2) = [1, 2] The following rules are removed: p1 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: plus_2#(s_1(x),y) -> plus_2#(x,y) and R consists of: r1: app(cons_0(),y) -> cons_1(y) r2: app(cons_1(x1),y) -> cons_2(x1,y) r3: app(inc_0(),y) -> inc_1(y) r4: app(map_0(),y) -> map_1(y) r5: app(map_1(x1),y) -> map_2(x1,y) r6: app(plus_0(),y) -> plus_1(y) r7: app(plus_1(x1),y) -> plus_2(x1,y) r8: app(s_0(),y) -> s_1(y) r9: plus_2(|0|_0(),y) -> y r10: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r11: inc_1(xs) -> map_2(plus_1(s_1(|0|_0())),xs) r12: map_2(f,nil_0()) -> nil_0() r13: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: plus_2#_A(x1,x2) = 0 s_1_A(x1) = max{10, x1 - 3} plus_2#!_A(x1,x2) = max{0, x1 - 11} s_1!_A(x1) = max{6, x1 - 6} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: plus_2#_A(x1,x2) = 0 s_1_A(x1) = max{9, x1 - 3} plus_2#!_A(x1,x2) = max{7, x1 - 10, x2 - 1} s_1!_A(x1) = max{6, x1 - 16} partial status: pi(plus_2#) = [1] pi(s_1) = [1] The following rules are removed: p1 Then no dependency pair remains.