YES We show the termination of the TRS R: app(app(|:|(),x),x) -> e() app(app(|:|(),e()),x) -> x app(app(|:|(),x),app(app(.(),x),y)) -> y app(app(|:|(),app(app(/(),x),y)),x) -> y app(app(/(),x),x) -> e() app(app(/(),x),e()) -> x app(app(/(),app(app(.(),y),x)),x) -> y app(app(/(),x),app(app(|:|(),y),x)) -> y app(app(.(),e()),x) -> x app(app(.(),x),e()) -> x app(app(.(),x),app(app(|:|(),x),y)) -> y app(app(.(),app(app(/(),y),x)),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(._0(),y) -> ._1(y) app(._1(x1),y) -> ._2(x1,y) app(/_0(),y) -> /_1(y) app(/_1(x1),y) -> /_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(|:|_0(),y) -> |:|_1(y) app(|:|_1(x1),y) -> |:|_2(x1,y) |:|_2(x,x) -> e_0() |:|_2(e_0(),x) -> x |:|_2(x,._2(x,y)) -> y |:|_2(/_2(x,y),x) -> y /_2(x,x) -> e_0() /_2(x,e_0()) -> x /_2(._2(y,x),x) -> y /_2(x,|:|_2(y,x)) -> y ._2(e_0(),x) -> x ._2(x,e_0()) -> x ._2(x,|:|_2(x,y)) -> y ._2(/_2(y,x),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#(._1(x1),y) -> ._2#(x1,y) p2: app#(/_1(x1),y) -> /_2#(x1,y) p3: app#(filter_1(x1),y) -> filter_2#(x1,y) p4: app#(filter2_3(x1,x2,x3),y) -> filter2_4#(x1,x2,x3,y) p5: app#(map_1(x1),y) -> map_2#(x1,y) p6: app#(|:|_1(x1),y) -> |:|_2#(x1,y) p7: map_2#(f,cons_2(x,xs)) -> app#(f,x) p8: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p9: filter_2#(f,cons_2(x,xs)) -> filter2_4#(app(f,x),f,x,xs) p10: filter_2#(f,cons_2(x,xs)) -> app#(f,x) p11: filter2_4#(true_0(),f,x,xs) -> filter_2#(f,xs) p12: filter2_4#(false_0(),f,x,xs) -> filter_2#(f,xs) and R consists of: r1: app(._0(),y) -> ._1(y) r2: app(._1(x1),y) -> ._2(x1,y) r3: app(/_0(),y) -> /_1(y) r4: app(/_1(x1),y) -> /_2(x1,y) r5: app(cons_0(),y) -> cons_1(y) r6: app(cons_1(x1),y) -> cons_2(x1,y) r7: app(filter_0(),y) -> filter_1(y) r8: app(filter_1(x1),y) -> filter_2(x1,y) r9: app(filter2_0(),y) -> filter2_1(y) r10: app(filter2_1(x1),y) -> filter2_2(x1,y) r11: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r12: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r13: app(map_0(),y) -> map_1(y) r14: app(map_1(x1),y) -> map_2(x1,y) r15: app(|:|_0(),y) -> |:|_1(y) r16: app(|:|_1(x1),y) -> |:|_2(x1,y) r17: |:|_2(x,x) -> e_0() r18: |:|_2(e_0(),x) -> x r19: |:|_2(x,._2(x,y)) -> y r20: |:|_2(/_2(x,y),x) -> y r21: /_2(x,x) -> e_0() r22: /_2(x,e_0()) -> x r23: /_2(._2(y,x),x) -> y r24: /_2(x,|:|_2(y,x)) -> y r25: ._2(e_0(),x) -> x r26: ._2(x,e_0()) -> x r27: ._2(x,|:|_2(x,y)) -> y r28: ._2(/_2(y,x),x) -> y r29: map_2(f,nil_0()) -> nil_0() r30: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r31: filter_2(f,nil_0()) -> nil_0() r32: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r33: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r34: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The estimated dependency graph contains the following SCCs: {p3, p4, p5, p7, p8, p9, p10, p11, p12} -- 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(._0(),y) -> ._1(y) r2: app(._1(x1),y) -> ._2(x1,y) r3: app(/_0(),y) -> /_1(y) r4: app(/_1(x1),y) -> /_2(x1,y) r5: app(cons_0(),y) -> cons_1(y) r6: app(cons_1(x1),y) -> cons_2(x1,y) r7: app(filter_0(),y) -> filter_1(y) r8: app(filter_1(x1),y) -> filter_2(x1,y) r9: app(filter2_0(),y) -> filter2_1(y) r10: app(filter2_1(x1),y) -> filter2_2(x1,y) r11: app(filter2_2(x1,x2),y) -> filter2_3(x1,x2,y) r12: app(filter2_3(x1,x2,x3),y) -> filter2_4(x1,x2,x3,y) r13: app(map_0(),y) -> map_1(y) r14: app(map_1(x1),y) -> map_2(x1,y) r15: app(|:|_0(),y) -> |:|_1(y) r16: app(|:|_1(x1),y) -> |:|_2(x1,y) r17: |:|_2(x,x) -> e_0() r18: |:|_2(e_0(),x) -> x r19: |:|_2(x,._2(x,y)) -> y r20: |:|_2(/_2(x,y),x) -> y r21: /_2(x,x) -> e_0() r22: /_2(x,e_0()) -> x r23: /_2(._2(y,x),x) -> y r24: /_2(x,|:|_2(y,x)) -> y r25: ._2(e_0(),x) -> x r26: ._2(x,e_0()) -> x r27: ._2(x,|:|_2(x,y)) -> y r28: ._2(/_2(y,x),x) -> y r29: map_2(f,nil_0()) -> nil_0() r30: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r31: filter_2(f,nil_0()) -> nil_0() r32: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r33: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r34: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The set of usable rules consists of r17, r18, r20, r22, r24, r29, r31 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{2, x1 - 30, x2 - 35} filter_1_A(x1) = max{2, x1 + 1} filter_2#_A(x1,x2) = max{2, x1 - 29, x2 - 35} cons_2_A(x1,x2) = max{x1 + 26, x2 + 36} map_1_A(x1) = max{2, x1 + 1} map_2#_A(x1,x2) = max{2, x1 - 29, x2 - 37} filter2_3_A(x1,x2,x3) = max{x1 + 1, x2 + 1, x3 + 29} filter2_4#_A(x1,x2,x3,x4) = max{2, x2 - 29, x3 - 9, x4 - 35} false_0_A = 97 app_A(x1,x2) = max{97, x1 - 3, x2 + 60} true_0_A = 97 |:|_2_A(x1,x2) = max{97, x1 + 1, x2 + 1} e_0_A = 2 /_2_A(x1,x2) = max{61, x1 + 1, x2 - 1} map_2_A(x1,x2) = max{123, x2 - 26} nil_0_A = 27 filter_2_A(x1,x2) = max{61, x1 - 38} app#!_A(x1,x2) = max{23, x2 + 13} filter_1!_A(x1) = max{10, x1 + 3} filter_2#!_A(x1,x2) = max{11, x2 - 2} cons_2!_A(x1,x2) = 4 map_1!_A(x1) = max{1, x1 - 32} map_2#!_A(x1,x2) = max{12, x2 - 12} filter2_3!_A(x1,x2,x3) = max{4, x1 - 32, x2 - 29, x3 - 1} filter2_4#!_A(x1,x2,x3,x4) = max{12, x4 - 1} false_0!_A = 3 app!_A(x1,x2) = max{x1 - 30, x2 + 25} true_0!_A = 12 |:|_2!_A(x1,x2) = max{13, x1 - 2, x2 - 1} e_0!_A = 12 /_2!_A(x1,x2) = max{11, x1 - 2, x2 - 1} map_2!_A(x1,x2) = max{8, x1 - 31, x2 - 86} nil_0!_A = 1 filter_2!_A(x1,x2) = max{2, x2 - 28} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: app#_A(x1,x2) = max{1, x1 - 11, x2 - 17} filter_1_A(x1) = x1 filter_2#_A(x1,x2) = max{1, x1 - 11, x2 - 17} cons_2_A(x1,x2) = max{16, x1 + 5, x2 + 5} map_1_A(x1) = max{10, x1 + 2} map_2#_A(x1,x2) = max{1, x1 - 9, x2 - 17} filter2_3_A(x1,x2,x3) = max{x1, x2, x3 + 5} filter2_4#_A(x1,x2,x3,x4) = max{1, x2 - 11, x3 - 12, x4 - 17} false_0_A = 8 app_A(x1,x2) = 6 true_0_A = 8 |:|_2_A(x1,x2) = max{2, x1 + 1, x2 + 1} e_0_A = 2 /_2_A(x1,x2) = max{2, x1 + 1, x2 - 1} map_2_A(x1,x2) = max{7, x1 - 4, x2 - 4} nil_0_A = 6 filter_2_A(x1,x2) = max{6, x1 - 4, x2 - 4} app#!_A(x1,x2) = max{2, x1 - 6} filter_1!_A(x1) = 5 filter_2#!_A(x1,x2) = max{9, x1 - 12, x2 - 20} cons_2!_A(x1,x2) = 0 map_1!_A(x1) = x1 + 4 map_2#!_A(x1,x2) = max{3, x1 - 5} filter2_3!_A(x1,x2,x3) = max{0, x1 - 10, x2 - 10, x3 - 17} filter2_4#!_A(x1,x2,x3,x4) = max{1, x3 - 16} false_0!_A = 8 app!_A(x1,x2) = max{5, x1 - 11, x2 - 18} true_0!_A = 10 |:|_2!_A(x1,x2) = max{4, x1 - 17, x2 - 19} e_0!_A = 5 /_2!_A(x1,x2) = max{4, x1 - 12, x2 - 19} map_2!_A(x1,x2) = max{0, x1 - 12, x2 - 17} nil_0!_A = 0 filter_2!_A(x1,x2) = 7 partial status: pi(app#) = [] pi(filter_1) = [] pi(filter_2#) = [] pi(cons_2) = [] pi(map_1) = [1] pi(map_2#) = [] pi(filter2_3) = [3] pi(filter2_4#) = [] pi(false_0) = [] pi(app) = [1, 2] pi(true_0) = [] pi(|:|_2) = [1, 2] pi(e_0) = [] pi(/_2) = [1, 2] pi(map_2) = [2] pi(nil_0) = [] pi(filter_2) = [1] The following rules are removed: p1, p2, p3, p4, p5, p6, p7, p8, p9 Then no dependency pair remains.