YES We show the termination of the TRS R: app(app(|:|(),app(app(|:|(),app(app(|:|(),app(app(|:|(),C()),x)),y)),z)),u) -> app(app(|:|(),app(app(|:|(),x),z)),app(app(|:|(),app(app(|:|(),app(app(|:|(),x),y)),z)),u)) 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)) app(app(filter(),f),nil()) -> nil() app(app(filter(),f),app(app(cons(),x),xs)) -> app(app(app(app(filter2(),app(f,x)),f),x),xs) app(app(app(app(filter2(),true()),f),x),xs) -> app(app(cons(),x),app(app(filter(),f),xs)) app(app(app(app(filter2(),false()),f),x),xs) -> app(app(filter(),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(filter_0(),y) -> filter_1(y) app(filter_1(x1),y) -> filter_2(x1,y) app(filter2_0(),y) -> filter2_1(y) app(filter2_1(x1),y) -> filter2_2(x1,y) app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) app(map_0(),y) -> map_1(y) app(map_1(x1),y) -> map_2(x1,y) app(|:|_0(),y) -> |:|_1(y) app(|:|_1(x1),y) -> |:|_2(x1,y) |:|_2(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2(|:|_2(x,z),|:|_2(|:|_2(|:|_2(x,y),z),u)) map_2(f,nil_0()) -> nil_0() map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) filter_2(f,nil_0()) -> nil_0() filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(filter_1(x1),y) -> filter_2#(x1,y) p2: app#(filter2_3(x1,x2,x3),y) -> filter2_4#(x1,x2,x3,y) p3: app#(map_1(x1),y) -> map_2#(x1,y) p4: app#(|:|_1(x1),y) -> |:|_2#(x1,y) p5: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(|:|_2(x,z),|:|_2(|:|_2(|:|_2(x,y),z),u)) p6: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(x,z) p7: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(|:|_2(|:|_2(x,y),z),u) p8: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(|:|_2(x,y),z) p9: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(x,y) p10: map_2#(f,cons_2(x,xs)) -> app#(f,x) p11: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p12: filter_2#(f,cons_2(x,xs)) -> filter2_4#(app(f,x),f,x,xs) p13: filter_2#(f,cons_2(x,xs)) -> app#(f,x) p14: filter2_4#(true_0(),f,x,xs) -> filter_2#(f,xs) p15: filter2_4#(false_0(),f,x,xs) -> filter_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(filter_0(),y) -> filter_1(y) r4: app(filter_1(x1),y) -> filter_2(x1,y) r5: app(filter2_0(),y) -> filter2_1(y) r6: app(filter2_1(x1),y) -> filter2_2(x1,y) r7: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r8: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r9: app(map_0(),y) -> map_1(y) r10: app(map_1(x1),y) -> map_2(x1,y) r11: app(|:|_0(),y) -> |:|_1(y) r12: app(|:|_1(x1),y) -> |:|_2(x1,y) r13: |:|_2(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2(|:|_2(x,z),|:|_2(|:|_2(|:|_2(x,y),z),u)) r14: map_2(f,nil_0()) -> nil_0() r15: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r16: filter_2(f,nil_0()) -> nil_0() r17: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r18: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r19: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p10, p11, p12, p13, p14, p15} {p5, p6, p7, p8, p9} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(filter_1(x1),y) -> filter_2#(x1,y) p2: filter_2#(f,cons_2(x,xs)) -> app#(f,x) p3: app#(map_1(x1),y) -> map_2#(x1,y) p4: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p5: map_2#(f,cons_2(x,xs)) -> app#(f,x) p6: app#(filter2_3(x1,x2,x3),y) -> filter2_4#(x1,x2,x3,y) p7: filter2_4#(false_0(),f,x,xs) -> filter_2#(f,xs) p8: filter_2#(f,cons_2(x,xs)) -> filter2_4#(app(f,x),f,x,xs) p9: filter2_4#(true_0(),f,x,xs) -> filter_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(filter_0(),y) -> filter_1(y) r4: app(filter_1(x1),y) -> filter_2(x1,y) r5: app(filter2_0(),y) -> filter2_1(y) r6: app(filter2_1(x1),y) -> filter2_2(x1,y) r7: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r8: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r9: app(map_0(),y) -> map_1(y) r10: app(map_1(x1),y) -> map_2(x1,y) r11: app(|:|_0(),y) -> |:|_1(y) r12: app(|:|_1(x1),y) -> |:|_2(x1,y) r13: |:|_2(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2(|:|_2(x,z),|:|_2(|:|_2(|:|_2(x,y),z),u)) r14: map_2(f,nil_0()) -> nil_0() r15: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r16: filter_2(f,nil_0()) -> nil_0() r17: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r18: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r19: filter2_4(false_0(),f,x,xs) -> filter_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!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: app#_A(x1,x2) = x1 + x2 filter_1_A(x1) = x1 + 3 filter_2#_A(x1,x2) = x1 + x2 + 3 cons_2_A(x1,x2) = x1 + x2 + 9 map_1_A(x1) = x1 + 3 map_2#_A(x1,x2) = x1 + x2 filter2_3_A(x1,x2,x3) = x1 + x2 + x3 + 7 filter2_4#_A(x1,x2,x3,x4) = x2 + x4 + 3 false_0_A() = 1 app_A(x1,x2) = x1 + x2 + 1 true_0_A() = 1 app#!_A(x1,x2) = x2 + 8 filter_1!_A(x1) = 5 filter_2#!_A(x1,x2) = x2 cons_2!_A(x1,x2) = x2 + 7 map_1!_A(x1) = 1 map_2#!_A(x1,x2) = x2 + 6 filter2_3!_A(x1,x2,x3) = x2 + x3 + 5 filter2_4#!_A(x1,x2,x3,x4) = x4 + 6 false_0!_A() = 1 app!_A(x1,x2) = 4 true_0!_A() = 1 2. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: app#_A(x1,x2) = x1 + x2 filter_1_A(x1) = x1 + 3 filter_2#_A(x1,x2) = x1 + x2 + 3 cons_2_A(x1,x2) = x1 + x2 + 9 map_1_A(x1) = x1 + 3 map_2#_A(x1,x2) = x1 + x2 filter2_3_A(x1,x2,x3) = x1 + x2 + x3 + 7 filter2_4#_A(x1,x2,x3,x4) = x2 + x4 + 3 false_0_A() = 1 app_A(x1,x2) = x1 + 1 true_0_A() = 1 app#!_A(x1,x2) = x2 + 12 filter_1!_A(x1) = 5 filter_2#!_A(x1,x2) = x2 + 4 cons_2!_A(x1,x2) = x1 + x2 + 11 map_1!_A(x1) = 1 map_2#!_A(x1,x2) = x2 + 2 filter2_3!_A(x1,x2,x3) = x1 + x2 + 8 filter2_4#!_A(x1,x2,x3,x4) = x4 + 9 false_0!_A() = 0 app!_A(x1,x2) = x2 + 9 true_0!_A() = 22 partial status: pi(app#) = [] pi(filter_1) = [1] pi(filter_2#) = [] pi(cons_2) = [1] pi(map_1) = [] pi(map_2#) = [] pi(filter2_3) = [] pi(filter2_4#) = [] pi(false_0) = [] pi(app) = [] pi(true_0) = [] The following rules are removed: p1, p2, p3, p4, p5, p6, p7, p8, p9 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(|:|_2(x,z),|:|_2(|:|_2(|:|_2(x,y),z),u)) p2: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(x,y) p3: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(|:|_2(x,y),z) p4: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(|:|_2(|:|_2(x,y),z),u) p5: |:|_2#(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2#(x,z) and R consists of: r1: app(cons_0(),y) -> cons_1(y) r2: app(cons_1(x1),y) -> cons_2(x1,y) r3: app(filter_0(),y) -> filter_1(y) r4: app(filter_1(x1),y) -> filter_2(x1,y) r5: app(filter2_0(),y) -> filter2_1(y) r6: app(filter2_1(x1),y) -> filter2_2(x1,y) r7: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r8: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r9: app(map_0(),y) -> map_1(y) r10: app(map_1(x1),y) -> map_2(x1,y) r11: app(|:|_0(),y) -> |:|_1(y) r12: app(|:|_1(x1),y) -> |:|_2(x1,y) r13: |:|_2(|:|_2(|:|_2(|:|_2(C_0(),x),y),z),u) -> |:|_2(|:|_2(x,z),|:|_2(|:|_2(|:|_2(x,y),z),u)) r14: map_2(f,nil_0()) -> nil_0() r15: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r16: filter_2(f,nil_0()) -> nil_0() r17: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r18: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r19: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The set of usable rules consists of r13 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!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: |:|_2#_A(x1,x2) = 0 |:|_2_A(x1,x2) = 2 C_0_A() = 3 |:|_2#!_A(x1,x2) = 2 |:|_2!_A(x1,x2) = 4 C_0!_A() = 3 2. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: |:|_2#_A(x1,x2) = 0 |:|_2_A(x1,x2) = 2 C_0_A() = 1 |:|_2#!_A(x1,x2) = 1 |:|_2!_A(x1,x2) = 1 C_0!_A() = 0 partial status: pi(|:|_2#) = [1] pi(|:|_2) = [1, 2] pi(C_0) = [] The following rules are removed: p1, p2, p3, p4, p5 Then no dependency pair remains.