YES We show the termination of the TRS R: ap(ap(map(),f),xs) -> ap(ap(ap(if(),ap(isEmpty(),xs)),f),xs) ap(ap(ap(if(),true()),f),xs) -> nil() ap(ap(ap(if(),false()),f),xs) -> ap(ap(cons(),ap(f,ap(last(),xs))),ap(ap(map(),f),ap(dropLast(),xs))) ap(isEmpty(),nil()) -> true() ap(isEmpty(),ap(ap(cons(),x),xs)) -> false() ap(last(),ap(ap(cons(),x),nil())) -> x ap(last(),ap(ap(cons(),x),ap(ap(cons(),y),ys))) -> ap(last(),ap(ap(cons(),y),ys)) ap(dropLast(),nil()) -> nil() ap(dropLast(),ap(ap(cons(),x),nil())) -> nil() ap(dropLast(),ap(ap(cons(),x),ap(ap(cons(),y),ys))) -> ap(ap(cons(),x),ap(dropLast(),ap(ap(cons(),y),ys))) Instead we prove termination of the uncurried system: ap(cons_0(),y) -> cons_1(y) ap(cons_1(x1),y) -> cons_2(x1,y) ap(dropLast_0(),y) -> dropLast_1(y) ap(if_0(),y) -> if_1(y) ap(if_1(x1),y) -> if_2(x1,y) ap(if_2(x1,x2),y) -> if_3(x1,x2,y) ap(isEmpty_0(),y) -> isEmpty_1(y) ap(last_0(),y) -> last_1(y) ap(map_0(),y) -> map_1(y) ap(map_1(x1),y) -> map_2(x1,y) map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) if_3(true_0(),f,xs) -> nil_0() if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) isEmpty_1(nil_0()) -> true_0() isEmpty_1(cons_2(x,xs)) -> false_0() last_1(cons_2(x,nil_0())) -> x last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) dropLast_1(nil_0()) -> nil_0() dropLast_1(cons_2(x,nil_0())) -> nil_0() dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: ap#(dropLast_0(),y) -> dropLast_1#(y) p2: ap#(if_2(x1,x2),y) -> if_3#(x1,x2,y) p3: ap#(isEmpty_0(),y) -> isEmpty_1#(y) p4: ap#(last_0(),y) -> last_1#(y) p5: ap#(map_1(x1),y) -> map_2#(x1,y) p6: map_2#(f,xs) -> if_3#(isEmpty_1(xs),f,xs) p7: map_2#(f,xs) -> isEmpty_1#(xs) p8: if_3#(false_0(),f,xs) -> ap#(f,last_1(xs)) p9: if_3#(false_0(),f,xs) -> last_1#(xs) p10: if_3#(false_0(),f,xs) -> map_2#(f,dropLast_1(xs)) p11: if_3#(false_0(),f,xs) -> dropLast_1#(xs) p12: last_1#(cons_2(x,cons_2(y,ys))) -> last_1#(cons_2(y,ys)) p13: dropLast_1#(cons_2(x,cons_2(y,ys))) -> dropLast_1#(cons_2(y,ys)) and R consists of: r1: ap(cons_0(),y) -> cons_1(y) r2: ap(cons_1(x1),y) -> cons_2(x1,y) r3: ap(dropLast_0(),y) -> dropLast_1(y) r4: ap(if_0(),y) -> if_1(y) r5: ap(if_1(x1),y) -> if_2(x1,y) r6: ap(if_2(x1,x2),y) -> if_3(x1,x2,y) r7: ap(isEmpty_0(),y) -> isEmpty_1(y) r8: ap(last_0(),y) -> last_1(y) r9: ap(map_0(),y) -> map_1(y) r10: ap(map_1(x1),y) -> map_2(x1,y) r11: map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) r12: if_3(true_0(),f,xs) -> nil_0() r13: if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) r14: isEmpty_1(nil_0()) -> true_0() r15: isEmpty_1(cons_2(x,xs)) -> false_0() r16: last_1(cons_2(x,nil_0())) -> x r17: last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) r18: dropLast_1(nil_0()) -> nil_0() r19: dropLast_1(cons_2(x,nil_0())) -> nil_0() r20: dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) The estimated dependency graph contains the following SCCs: {p2, p5, p6, p8, p10} {p13} {p12} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if_3#(false_0(),f,xs) -> ap#(f,last_1(xs)) p2: ap#(map_1(x1),y) -> map_2#(x1,y) p3: map_2#(f,xs) -> if_3#(isEmpty_1(xs),f,xs) p4: if_3#(false_0(),f,xs) -> map_2#(f,dropLast_1(xs)) p5: ap#(if_2(x1,x2),y) -> if_3#(x1,x2,y) and R consists of: r1: ap(cons_0(),y) -> cons_1(y) r2: ap(cons_1(x1),y) -> cons_2(x1,y) r3: ap(dropLast_0(),y) -> dropLast_1(y) r4: ap(if_0(),y) -> if_1(y) r5: ap(if_1(x1),y) -> if_2(x1,y) r6: ap(if_2(x1,x2),y) -> if_3(x1,x2,y) r7: ap(isEmpty_0(),y) -> isEmpty_1(y) r8: ap(last_0(),y) -> last_1(y) r9: ap(map_0(),y) -> map_1(y) r10: ap(map_1(x1),y) -> map_2(x1,y) r11: map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) r12: if_3(true_0(),f,xs) -> nil_0() r13: if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) r14: isEmpty_1(nil_0()) -> true_0() r15: isEmpty_1(cons_2(x,xs)) -> false_0() r16: last_1(cons_2(x,nil_0())) -> x r17: last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) r18: dropLast_1(nil_0()) -> nil_0() r19: dropLast_1(cons_2(x,nil_0())) -> nil_0() r20: dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) The set of usable rules consists of r14, r15, r16, r17, r18, r19, r20 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: if_3#_A(x1,x2,x3) = max{x1 - 23, x2 + 18, x3 + 16} false_0_A = 54 ap#_A(x1,x2) = max{x1 - 4, x2 + 18} last_1_A(x1) = max{12, x1 - 4} map_1_A(x1) = max{56, x1 + 41} map_2#_A(x1,x2) = max{x1 + 18, x2 + 16} isEmpty_1_A(x1) = max{41, x1 + 39} dropLast_1_A(x1) = max{15, x1} if_2_A(x1,x2) = max{x1 + 19, x2 + 22} nil_0_A = 14 true_0_A = 13 cons_2_A(x1,x2) = max{15, x1 + 5, x2 + 5} base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: if_3#_A(x1,x2,x3) = x2 + x3 + 3 false_0_A() = 1 ap#_A(x1,x2) = x1 + x2 last_1_A(x1) = x1 + 3 map_1_A(x1) = x1 + 3 map_2#_A(x1,x2) = x1 + x2 + 3 isEmpty_1_A(x1) = x1 + 3 dropLast_1_A(x1) = x1 if_2_A(x1,x2) = x1 + x2 + 5 nil_0_A() = 9 true_0_A() = 1 cons_2_A(x1,x2) = x1 + x2 + 5 if_3#!_A(x1,x2,x3) = 0 false_0!_A() = 2 ap#!_A(x1,x2) = 1 last_1!_A(x1) = 1 map_1!_A(x1) = 4 map_2#!_A(x1,x2) = 0 isEmpty_1!_A(x1) = 3 dropLast_1!_A(x1) = 4 if_2!_A(x1,x2) = x1 + x2 + 1 nil_0!_A() = 4 true_0!_A() = 0 cons_2!_A(x1,x2) = 1 partial status: pi(if_3#) = [] pi(false_0) = [] pi(ap#) = [2] pi(last_1) = [] pi(map_1) = [1] pi(map_2#) = [] pi(isEmpty_1) = [] pi(dropLast_1) = [] pi(if_2) = [2] pi(nil_0) = [] pi(true_0) = [] pi(cons_2) = [] The following rules are removed: p1, p2, p5 -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: map_2#(f,xs) -> if_3#(isEmpty_1(xs),f,xs) p2: if_3#(false_0(),f,xs) -> map_2#(f,dropLast_1(xs)) and R consists of: r1: ap(cons_0(),y) -> cons_1(y) r2: ap(cons_1(x1),y) -> cons_2(x1,y) r3: ap(dropLast_0(),y) -> dropLast_1(y) r4: ap(if_0(),y) -> if_1(y) r5: ap(if_1(x1),y) -> if_2(x1,y) r6: ap(if_2(x1,x2),y) -> if_3(x1,x2,y) r7: ap(isEmpty_0(),y) -> isEmpty_1(y) r8: ap(last_0(),y) -> last_1(y) r9: ap(map_0(),y) -> map_1(y) r10: ap(map_1(x1),y) -> map_2(x1,y) r11: map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) r12: if_3(true_0(),f,xs) -> nil_0() r13: if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) r14: isEmpty_1(nil_0()) -> true_0() r15: isEmpty_1(cons_2(x,xs)) -> false_0() r16: last_1(cons_2(x,nil_0())) -> x r17: last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) r18: dropLast_1(nil_0()) -> nil_0() r19: dropLast_1(cons_2(x,nil_0())) -> nil_0() r20: dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: map_2#(f,xs) -> if_3#(isEmpty_1(xs),f,xs) p2: if_3#(false_0(),f,xs) -> map_2#(f,dropLast_1(xs)) and R consists of: r1: ap(cons_0(),y) -> cons_1(y) r2: ap(cons_1(x1),y) -> cons_2(x1,y) r3: ap(dropLast_0(),y) -> dropLast_1(y) r4: ap(if_0(),y) -> if_1(y) r5: ap(if_1(x1),y) -> if_2(x1,y) r6: ap(if_2(x1,x2),y) -> if_3(x1,x2,y) r7: ap(isEmpty_0(),y) -> isEmpty_1(y) r8: ap(last_0(),y) -> last_1(y) r9: ap(map_0(),y) -> map_1(y) r10: ap(map_1(x1),y) -> map_2(x1,y) r11: map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) r12: if_3(true_0(),f,xs) -> nil_0() r13: if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) r14: isEmpty_1(nil_0()) -> true_0() r15: isEmpty_1(cons_2(x,xs)) -> false_0() r16: last_1(cons_2(x,nil_0())) -> x r17: last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) r18: dropLast_1(nil_0()) -> nil_0() r19: dropLast_1(cons_2(x,nil_0())) -> nil_0() r20: dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) The set of usable rules consists of r12, r14, r15, r18, r19, r20 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: map_2#_A(x1,x2) = x2 + 8 if_3#_A(x1,x2,x3) = max{x1 - 8, x3 + 7} isEmpty_1_A(x1) = max{7, x1 - 3} false_0_A = 62 dropLast_1_A(x1) = max{45, x1 - 2} if_3_A(x1,x2,x3) = max{67, x1 + 2, x2 - 65, x3 - 3} true_0_A = 41 nil_0_A = 45 cons_2_A(x1,x2) = max{66, x2 + 22} base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: map_2#_A(x1,x2) = 0 if_3#_A(x1,x2,x3) = 0 isEmpty_1_A(x1) = x1 + 2 false_0_A() = 1 dropLast_1_A(x1) = x1 + 1 if_3_A(x1,x2,x3) = 4 true_0_A() = 1 nil_0_A() = 0 cons_2_A(x1,x2) = 5 map_2#!_A(x1,x2) = x1 + x2 + 8 if_3#!_A(x1,x2,x3) = 7 isEmpty_1!_A(x1) = 1 false_0!_A() = 7 dropLast_1!_A(x1) = 6 if_3!_A(x1,x2,x3) = x3 + 2 true_0!_A() = 0 nil_0!_A() = 5 cons_2!_A(x1,x2) = 4 partial status: pi(map_2#) = [] pi(if_3#) = [] pi(isEmpty_1) = [] pi(false_0) = [] pi(dropLast_1) = [] pi(if_3) = [1] pi(true_0) = [] pi(nil_0) = [] pi(cons_2) = [] The following rules are removed: p1, p2 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: dropLast_1#(cons_2(x,cons_2(y,ys))) -> dropLast_1#(cons_2(y,ys)) and R consists of: r1: ap(cons_0(),y) -> cons_1(y) r2: ap(cons_1(x1),y) -> cons_2(x1,y) r3: ap(dropLast_0(),y) -> dropLast_1(y) r4: ap(if_0(),y) -> if_1(y) r5: ap(if_1(x1),y) -> if_2(x1,y) r6: ap(if_2(x1,x2),y) -> if_3(x1,x2,y) r7: ap(isEmpty_0(),y) -> isEmpty_1(y) r8: ap(last_0(),y) -> last_1(y) r9: ap(map_0(),y) -> map_1(y) r10: ap(map_1(x1),y) -> map_2(x1,y) r11: map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) r12: if_3(true_0(),f,xs) -> nil_0() r13: if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) r14: isEmpty_1(nil_0()) -> true_0() r15: isEmpty_1(cons_2(x,xs)) -> false_0() r16: last_1(cons_2(x,nil_0())) -> x r17: last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) r18: dropLast_1(nil_0()) -> nil_0() r19: dropLast_1(cons_2(x,nil_0())) -> nil_0() r20: dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) The set of usable rules consists of r18 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: dropLast_1#_A(x1) = max{53, x1 + 20} cons_2_A(x1,x2) = max{34, x1 - 81, x2 + 18} dropLast_1_A(x1) = max{17, x1 + 3} nil_0_A = 4 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: dropLast_1#_A(x1) = x1 cons_2_A(x1,x2) = x1 + x2 + 5 dropLast_1_A(x1) = x1 + 3 nil_0_A() = 8 dropLast_1#!_A(x1) = 8 cons_2!_A(x1,x2) = x2 + 7 dropLast_1!_A(x1) = x1 + 1 nil_0!_A() = 1 partial status: pi(dropLast_1#) = [1] pi(cons_2) = [] pi(dropLast_1) = [1] pi(nil_0) = [] 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: last_1#(cons_2(x,cons_2(y,ys))) -> last_1#(cons_2(y,ys)) and R consists of: r1: ap(cons_0(),y) -> cons_1(y) r2: ap(cons_1(x1),y) -> cons_2(x1,y) r3: ap(dropLast_0(),y) -> dropLast_1(y) r4: ap(if_0(),y) -> if_1(y) r5: ap(if_1(x1),y) -> if_2(x1,y) r6: ap(if_2(x1,x2),y) -> if_3(x1,x2,y) r7: ap(isEmpty_0(),y) -> isEmpty_1(y) r8: ap(last_0(),y) -> last_1(y) r9: ap(map_0(),y) -> map_1(y) r10: ap(map_1(x1),y) -> map_2(x1,y) r11: map_2(f,xs) -> if_3(isEmpty_1(xs),f,xs) r12: if_3(true_0(),f,xs) -> nil_0() r13: if_3(false_0(),f,xs) -> cons_2(ap(f,last_1(xs)),map_2(f,dropLast_1(xs))) r14: isEmpty_1(nil_0()) -> true_0() r15: isEmpty_1(cons_2(x,xs)) -> false_0() r16: last_1(cons_2(x,nil_0())) -> x r17: last_1(cons_2(x,cons_2(y,ys))) -> last_1(cons_2(y,ys)) r18: dropLast_1(nil_0()) -> nil_0() r19: dropLast_1(cons_2(x,nil_0())) -> nil_0() r20: dropLast_1(cons_2(x,cons_2(y,ys))) -> cons_2(x,dropLast_1(cons_2(y,ys))) The set of usable rules consists of r18 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: last_1#_A(x1) = 9 cons_2_A(x1,x2) = max{39, x1 + 14, x2 + 5} dropLast_1_A(x1) = x1 + 6 nil_0_A = 10 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: last_1#_A(x1) = x1 cons_2_A(x1,x2) = x1 + x2 + 5 dropLast_1_A(x1) = x1 + 3 nil_0_A() = 8 last_1#!_A(x1) = x1 + 8 cons_2!_A(x1,x2) = x2 + 7 dropLast_1!_A(x1) = x1 + 1 nil_0!_A() = 1 partial status: pi(last_1#) = [] pi(cons_2) = [] pi(dropLast_1) = [1] pi(nil_0) = [] The following rules are removed: p1 Then no dependency pair remains.