YES We show the termination of the TRS R: app(app(ack(),|0|()),y) -> app(succ(),y) app(app(ack(),app(succ(),x)),y) -> app(app(ack(),x),app(succ(),|0|())) app(app(ack(),app(succ(),x)),app(succ(),y)) -> app(app(ack(),x),app(app(ack(),app(succ(),x)),y)) 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(ack_0(),y) -> ack_1(y) app(ack_1(x1),y) -> ack_2(x1,y) 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(succ_0(),y) -> succ_1(y) ack_2(|0|_0(),y) -> succ_1(y) ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) 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#(ack_1(x1),y) -> ack_2#(x1,y) p2: app#(filter_1(x1),y) -> filter_2#(x1,y) p3: app#(filter2_3(x1,x2,x3),y) -> filter2_4#(x1,x2,x3,y) p4: app#(map_1(x1),y) -> map_2#(x1,y) p5: ack_2#(succ_1(x),y) -> ack_2#(x,succ_1(|0|_0())) p6: ack_2#(succ_1(x),succ_1(y)) -> ack_2#(x,ack_2(succ_1(x),y)) p7: ack_2#(succ_1(x),succ_1(y)) -> ack_2#(succ_1(x),y) p8: map_2#(f,cons_2(x,xs)) -> app#(f,x) p9: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p10: filter_2#(f,cons_2(x,xs)) -> filter2_4#(app(f,x),f,x,xs) p11: filter_2#(f,cons_2(x,xs)) -> app#(f,x) p12: filter2_4#(true_0(),f,x,xs) -> filter_2#(f,xs) p13: filter2_4#(false_0(),f,x,xs) -> filter_2#(f,xs) and R consists of: r1: app(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The estimated dependency graph contains the following SCCs: {p2, p3, p4, p8, p9, p10, p11, p12, p13} {p5, p6, p7} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: map_2#(f,cons_2(x,xs)) -> app#(f,x) p2: app#(map_1(x1),y) -> map_2#(x1,y) p3: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p4: app#(filter2_3(x1,x2,x3),y) -> filter2_4#(x1,x2,x3,y) p5: filter2_4#(false_0(),f,x,xs) -> filter_2#(f,xs) p6: filter_2#(f,cons_2(x,xs)) -> app#(f,x) p7: app#(filter_1(x1),y) -> filter_2#(x1,y) 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(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: 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: map_2#_A(x1,x2) = x1 + x2 cons_2_A(x1,x2) = x1 + x2 + 5 app#_A(x1,x2) = x1 + x2 map_1_A(x1) = x1 + 3 filter2_3_A(x1,x2,x3) = x1 + x2 + x3 + 7 filter2_4#_A(x1,x2,x3,x4) = x2 + x4 + 7 false_0_A() = 1 filter_2#_A(x1,x2) = x1 + x2 + 7 filter_1_A(x1) = x1 + 7 app_A(x1,x2) = x1 + x2 + 1 true_0_A() = 1 map_2#!_A(x1,x2) = 6 cons_2!_A(x1,x2) = 4 app#!_A(x1,x2) = 5 map_1!_A(x1) = 7 filter2_3!_A(x1,x2,x3) = x1 + x2 + x3 + 7 filter2_4#!_A(x1,x2,x3,x4) = 6 false_0!_A() = 9 filter_2#!_A(x1,x2) = 6 filter_1!_A(x1) = x1 + 7 app!_A(x1,x2) = 2 true_0!_A() = 5 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) = x2 cons_2_A(x1,x2) = x1 + x2 + 5 app#_A(x1,x2) = x2 map_1_A(x1) = 3 filter2_3_A(x1,x2,x3) = x1 + x2 + x3 filter2_4#_A(x1,x2,x3,x4) = x4 false_0_A() = 1 filter_2#_A(x1,x2) = x2 filter_1_A(x1) = 3 app_A(x1,x2) = x1 + x2 + 1 true_0_A() = 1 map_2#!_A(x1,x2) = 1 cons_2!_A(x1,x2) = x2 + 4 app#!_A(x1,x2) = 0 map_1!_A(x1) = 2 filter2_3!_A(x1,x2,x3) = 16 filter2_4#!_A(x1,x2,x3,x4) = x2 + x4 + 15 false_0!_A() = 0 filter_2#!_A(x1,x2) = x1 + x2 + 11 filter_1!_A(x1) = 7 app!_A(x1,x2) = 5 true_0!_A() = 10 partial status: pi(map_2#) = [1] pi(cons_2) = [] pi(app#) = [1] pi(map_1) = [1] pi(filter2_3) = [2] pi(filter2_4#) = [2] pi(false_0) = [] pi(filter_2#) = [1] pi(filter_1) = [1] pi(app) = [] pi(true_0) = [] The following rules are removed: p1, p2, p4, p5, p6, p7, p8, p9 -- 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(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: filter2_4(false_0(),f,x,xs) -> filter_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(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: 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: map_2#_A(x1,x2) = x2 cons_2_A(x1,x2) = x2 + 2 map_2#!_A(x1,x2) = x2 + 6 cons_2!_A(x1,x2) = 7 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) = x2 cons_2_A(x1,x2) = x1 + x2 + 9 map_2#!_A(x1,x2) = x2 + 30 cons_2!_A(x1,x2) = 29 partial status: pi(map_2#) = [1] pi(cons_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: ack_2#(succ_1(x),y) -> ack_2#(x,succ_1(|0|_0())) p2: ack_2#(succ_1(x),succ_1(y)) -> ack_2#(succ_1(x),y) p3: ack_2#(succ_1(x),succ_1(y)) -> ack_2#(x,ack_2(succ_1(x),y)) and R consists of: r1: app(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The set of usable rules consists of r14 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: ack_2#_A(x1,x2) = 0 succ_1_A(x1) = 1 |0|_0_A() = 2 ack_2_A(x1,x2) = x1 + 2 ack_2#!_A(x1,x2) = 6 succ_1!_A(x1) = 6 |0|_0!_A() = 5 ack_2!_A(x1,x2) = x1 + 5 2. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: ack_2#_A(x1,x2) = 0 succ_1_A(x1) = 1 |0|_0_A() = 0 ack_2_A(x1,x2) = x1 + 1 ack_2#!_A(x1,x2) = 1 succ_1!_A(x1) = 1 |0|_0!_A() = 0 ack_2!_A(x1,x2) = 1 partial status: pi(ack_2#) = [1] pi(succ_1) = [1] pi(|0|_0) = [] pi(ack_2) = [2] The following rules are removed: p1, p3 -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: ack_2#(succ_1(x),succ_1(y)) -> ack_2#(succ_1(x),y) and R consists of: r1: app(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: filter2_4(false_0(),f,x,xs) -> filter_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: ack_2#(succ_1(x),succ_1(y)) -> ack_2#(succ_1(x),y) and R consists of: r1: app(ack_0(),y) -> ack_1(y) r2: app(ack_1(x1),y) -> ack_2(x1,y) r3: app(cons_0(),y) -> cons_1(y) r4: app(cons_1(x1),y) -> cons_2(x1,y) r5: app(filter_0(),y) -> filter_1(y) r6: app(filter_1(x1),y) -> filter_2(x1,y) r7: app(filter2_0(),y) -> filter2_1(y) r8: app(filter2_1(x1),y) -> filter2_2(x1,y) r9: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r10: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r11: app(map_0(),y) -> map_1(y) r12: app(map_1(x1),y) -> map_2(x1,y) r13: app(succ_0(),y) -> succ_1(y) r14: ack_2(|0|_0(),y) -> succ_1(y) r15: ack_2(succ_1(x),y) -> ack_2(x,succ_1(|0|_0())) r16: ack_2(succ_1(x),succ_1(y)) -> ack_2(x,ack_2(succ_1(x),y)) r17: map_2(f,nil_0()) -> nil_0() r18: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r19: filter_2(f,nil_0()) -> nil_0() r20: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r21: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r22: 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: ack_2#_A(x1,x2) = 0 succ_1_A(x1) = 2 ack_2#!_A(x1,x2) = 6 succ_1!_A(x1) = 5 2. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: ack_2#_A(x1,x2) = x2 succ_1_A(x1) = x1 + 1 ack_2#!_A(x1,x2) = x1 + x2 + 2 succ_1!_A(x1) = 2 partial status: pi(ack_2#) = [1] pi(succ_1) = [1] The following rules are removed: p1 Then no dependency pair remains.