YES We show the termination of the TRS R: app(rev(),nil()) -> nil() app(rev(),app(app(cons(),x),l)) -> app(app(cons(),app(app(rev1(),x),l)),app(app(rev2(),x),l)) app(app(rev1(),|0|()),nil()) -> |0|() app(app(rev1(),app(s(),x)),nil()) -> app(s(),x) app(app(rev1(),x),app(app(cons(),y),l)) -> app(app(rev1(),y),l) app(app(rev2(),x),nil()) -> nil() app(app(rev2(),x),app(app(cons(),y),l)) -> app(rev(),app(app(cons(),x),app(app(rev2(),y),l))) 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(rev_0(),y) -> rev_1(y) app(rev1_0(),y) -> rev1_1(y) app(rev1_1(x1),y) -> rev1_2(x1,y) app(rev2_0(),y) -> rev2_1(y) app(rev2_1(x1),y) -> rev2_2(x1,y) app(s_0(),y) -> s_1(y) rev_1(nil_0()) -> nil_0() rev_1(cons_2(x,l)) -> cons_2(rev1_2(x,l),rev2_2(x,l)) rev1_2(|0|_0(),nil_0()) -> |0|_0() rev1_2(s_1(x),nil_0()) -> s_1(x) rev1_2(x,cons_2(y,l)) -> rev1_2(y,l) rev2_2(x,nil_0()) -> nil_0() rev2_2(x,cons_2(y,l)) -> rev_1(cons_2(x,rev2_2(y,l))) 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#(rev_0(),y) -> rev_1#(y) p5: app#(rev1_1(x1),y) -> rev1_2#(x1,y) p6: app#(rev2_1(x1),y) -> rev2_2#(x1,y) p7: rev_1#(cons_2(x,l)) -> rev1_2#(x,l) p8: rev_1#(cons_2(x,l)) -> rev2_2#(x,l) p9: rev1_2#(x,cons_2(y,l)) -> rev1_2#(y,l) p10: rev2_2#(x,cons_2(y,l)) -> rev_1#(cons_2(x,rev2_2(y,l))) p11: rev2_2#(x,cons_2(y,l)) -> rev2_2#(y,l) p12: map_2#(f,cons_2(x,xs)) -> app#(f,x) p13: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs) p14: filter_2#(f,cons_2(x,xs)) -> filter2_4#(app(f,x),f,x,xs) p15: filter_2#(f,cons_2(x,xs)) -> app#(f,x) p16: filter2_4#(true_0(),f,x,xs) -> filter_2#(f,xs) p17: 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(rev_0(),y) -> rev_1(y) r12: app(rev1_0(),y) -> rev1_1(y) r13: app(rev1_1(x1),y) -> rev1_2(x1,y) r14: app(rev2_0(),y) -> rev2_1(y) r15: app(rev2_1(x1),y) -> rev2_2(x1,y) r16: app(s_0(),y) -> s_1(y) r17: rev_1(nil_0()) -> nil_0() r18: rev_1(cons_2(x,l)) -> cons_2(rev1_2(x,l),rev2_2(x,l)) r19: rev1_2(|0|_0(),nil_0()) -> |0|_0() r20: rev1_2(s_1(x),nil_0()) -> s_1(x) r21: rev1_2(x,cons_2(y,l)) -> rev1_2(y,l) r22: rev2_2(x,nil_0()) -> nil_0() r23: rev2_2(x,cons_2(y,l)) -> rev_1(cons_2(x,rev2_2(y,l))) r24: map_2(f,nil_0()) -> nil_0() r25: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r26: filter_2(f,nil_0()) -> nil_0() r27: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r28: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r29: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p12, p13, p14, p15, p16, p17} {p8, p10, p11} {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(rev_0(),y) -> rev_1(y) r12: app(rev1_0(),y) -> rev1_1(y) r13: app(rev1_1(x1),y) -> rev1_2(x1,y) r14: app(rev2_0(),y) -> rev2_1(y) r15: app(rev2_1(x1),y) -> rev2_2(x1,y) r16: app(s_0(),y) -> s_1(y) r17: rev_1(nil_0()) -> nil_0() r18: rev_1(cons_2(x,l)) -> cons_2(rev1_2(x,l),rev2_2(x,l)) r19: rev1_2(|0|_0(),nil_0()) -> |0|_0() r20: rev1_2(s_1(x),nil_0()) -> s_1(x) r21: rev1_2(x,cons_2(y,l)) -> rev1_2(y,l) r22: rev2_2(x,nil_0()) -> nil_0() r23: rev2_2(x,cons_2(y,l)) -> rev_1(cons_2(x,rev2_2(y,l))) r24: map_2(f,nil_0()) -> nil_0() r25: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r26: filter_2(f,nil_0()) -> nil_0() r27: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r28: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r29: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The set of usable rules consists of r5, r6, r12, r14, r17, r19, r20, r26 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: app#_A(x1,x2) = max{43, x1 + 33, x2 + 35} filter_1_A(x1) = max{16, x1 + 2} filter_2#_A(x1,x2) = max{34, x1 + 33, x2 + 24} cons_2_A(x1,x2) = max{19, x1 + 13, x2 + 14} map_1_A(x1) = max{21, x1 + 12} map_2#_A(x1,x2) = max{x1 + 44, x2 + 23} filter2_3_A(x1,x2,x3) = max{x1 - 48, x2, x3 - 14} filter2_4#_A(x1,x2,x3,x4) = max{43, x2 + 33, x3 + 14, x4 + 33} false_0_A = 15 app_A(x1,x2) = max{32, x1 + 14, x2 + 13} true_0_A = 15 filter2_0_A = 12 filter2_1_A(x1) = max{11, x1 - 48} filter2_2_A(x1,x2) = max{12, x1 - 47, x2 - 15} rev1_0_A = 1 rev1_1_A(x1) = max{16, x1 - 1} rev2_0_A = 34 rev2_1_A(x1) = max{33, x1 - 15} rev_1_A(x1) = max{33, x1} nil_0_A = 4 rev1_2_A(x1,x2) = max{2, x1, x2} |0|_0_A = 3 s_1_A(x1) = 33 filter_2_A(x1,x2) = max{31, x1 - 34, x2 - 16} base order 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 cons_2_A(x1,x2) = x1 + x2 + 6 map_1_A(x1) = x1 + 2 map_2#_A(x1,x2) = x1 + x2 filter2_3_A(x1,x2,x3) = x1 + x2 + x3 filter2_4#_A(x1,x2,x3,x4) = x2 + x4 false_0_A() = 1 app_A(x1,x2) = x1 + x2 + 1 true_0_A() = 1 filter2_0_A() = 1 filter2_1_A(x1) = x1 filter2_2_A(x1,x2) = x1 + x2 rev1_0_A() = 0 rev1_1_A(x1) = x1 rev2_0_A() = 0 rev2_1_A(x1) = 0 rev_1_A(x1) = 2 nil_0_A() = 0 rev1_2_A(x1,x2) = x1 + x2 + 2 |0|_0_A() = 1 s_1_A(x1) = x1 + 2 filter_2_A(x1,x2) = x1 app#!_A(x1,x2) = x2 + 4 filter_1!_A(x1) = 0 filter_2#!_A(x1,x2) = x2 + 1 cons_2!_A(x1,x2) = x2 + 3 map_1!_A(x1) = 5 map_2#!_A(x1,x2) = x2 + 6 filter2_3!_A(x1,x2,x3) = x1 + x2 + x3 + 12 filter2_4#!_A(x1,x2,x3,x4) = x4 + 2 false_0!_A() = 11 app!_A(x1,x2) = 6 true_0!_A() = 2 filter2_0!_A() = 0 filter2_1!_A(x1) = 1 filter2_2!_A(x1,x2) = 2 rev1_0!_A() = 8 rev1_1!_A(x1) = 7 rev2_0!_A() = 9 rev2_1!_A(x1) = 8 rev_1!_A(x1) = 8 nil_0!_A() = 9 rev1_2!_A(x1,x2) = 2 |0|_0!_A() = 0 s_1!_A(x1) = 10 filter_2!_A(x1,x2) = x2 + 10 partial status: pi(app#) = [] pi(filter_1) = [] pi(filter_2#) = [1] pi(cons_2) = [2] pi(map_1) = [] pi(map_2#) = [1, 2] pi(filter2_3) = [2] pi(filter2_4#) = [2, 4] pi(false_0) = [] pi(app) = [2] pi(true_0) = [] pi(filter2_0) = [] pi(filter2_1) = [] pi(filter2_2) = [] pi(rev1_0) = [] pi(rev1_1) = [] pi(rev2_0) = [] pi(rev2_1) = [] pi(rev_1) = [1] pi(nil_0) = [] pi(rev1_2) = [1, 2] pi(|0|_0) = [] pi(s_1) = [] pi(filter_2) = [] 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: rev2_2#(x,cons_2(y,l)) -> rev_1#(cons_2(x,rev2_2(y,l))) p2: rev_1#(cons_2(x,l)) -> rev2_2#(x,l) p3: rev2_2#(x,cons_2(y,l)) -> rev2_2#(y,l) 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(rev_0(),y) -> rev_1(y) r12: app(rev1_0(),y) -> rev1_1(y) r13: app(rev1_1(x1),y) -> rev1_2(x1,y) r14: app(rev2_0(),y) -> rev2_1(y) r15: app(rev2_1(x1),y) -> rev2_2(x1,y) r16: app(s_0(),y) -> s_1(y) r17: rev_1(nil_0()) -> nil_0() r18: rev_1(cons_2(x,l)) -> cons_2(rev1_2(x,l),rev2_2(x,l)) r19: rev1_2(|0|_0(),nil_0()) -> |0|_0() r20: rev1_2(s_1(x),nil_0()) -> s_1(x) r21: rev1_2(x,cons_2(y,l)) -> rev1_2(y,l) r22: rev2_2(x,nil_0()) -> nil_0() r23: rev2_2(x,cons_2(y,l)) -> rev_1(cons_2(x,rev2_2(y,l))) r24: map_2(f,nil_0()) -> nil_0() r25: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r26: filter_2(f,nil_0()) -> nil_0() r27: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r28: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r29: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The set of usable rules consists of r16, r17, r18, r19, r20, r21, r22, r23 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: rev2_2#_A(x1,x2) = max{20, x2 + 3} cons_2_A(x1,x2) = max{43, x2 + 19} rev_1#_A(x1) = max{23, x1 + 2} rev2_2_A(x1,x2) = max{21, x2} app_A(x1,x2) = max{x1 - 7, x2 + 6} s_0_A = 31 s_1_A(x1) = 23 rev_1_A(x1) = max{43, x1} nil_0_A = 22 rev1_2_A(x1,x2) = max{24, x2 + 6} |0|_0_A = 27 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: rev2_2#_A(x1,x2) = 0 cons_2_A(x1,x2) = x1 rev_1#_A(x1) = 0 rev2_2_A(x1,x2) = x2 + 2 app_A(x1,x2) = 2 s_0_A() = 1 s_1_A(x1) = 0 rev_1_A(x1) = 2 nil_0_A() = 1 rev1_2_A(x1,x2) = 1 |0|_0_A() = 0 rev2_2#!_A(x1,x2) = 1 cons_2!_A(x1,x2) = 2 rev_1#!_A(x1) = 0 rev2_2!_A(x1,x2) = x1 + x2 + 10 app!_A(x1,x2) = 8 s_0!_A() = 8 s_1!_A(x1) = 7 rev_1!_A(x1) = 3 nil_0!_A() = 6 rev1_2!_A(x1,x2) = x1 + x2 + 7 |0|_0!_A() = 7 partial status: pi(rev2_2#) = [] pi(cons_2) = [] pi(rev_1#) = [1] pi(rev2_2) = [2] pi(app) = [] pi(s_0) = [] pi(s_1) = [] pi(rev_1) = [] pi(nil_0) = [] pi(rev1_2) = [] pi(|0|_0) = [] The following rules are removed: p1, p2, p3 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: rev1_2#(x,cons_2(y,l)) -> rev1_2#(y,l) 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(rev_0(),y) -> rev_1(y) r12: app(rev1_0(),y) -> rev1_1(y) r13: app(rev1_1(x1),y) -> rev1_2(x1,y) r14: app(rev2_0(),y) -> rev2_1(y) r15: app(rev2_1(x1),y) -> rev2_2(x1,y) r16: app(s_0(),y) -> s_1(y) r17: rev_1(nil_0()) -> nil_0() r18: rev_1(cons_2(x,l)) -> cons_2(rev1_2(x,l),rev2_2(x,l)) r19: rev1_2(|0|_0(),nil_0()) -> |0|_0() r20: rev1_2(s_1(x),nil_0()) -> s_1(x) r21: rev1_2(x,cons_2(y,l)) -> rev1_2(y,l) r22: rev2_2(x,nil_0()) -> nil_0() r23: rev2_2(x,cons_2(y,l)) -> rev_1(cons_2(x,rev2_2(y,l))) r24: map_2(f,nil_0()) -> nil_0() r25: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs)) r26: filter_2(f,nil_0()) -> nil_0() r27: filter_2(f,cons_2(x,xs)) -> filter2_4(app(f,x),f,x,xs) r28: filter2_4(true_0(),f,x,xs) -> cons_2(x,filter_2(f,xs)) r29: filter2_4(false_0(),f,x,xs) -> filter_2(f,xs) The set of usable rules consists of r19, r26 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: rev1_2#_A(x1,x2) = 0 cons_2_A(x1,x2) = max{42, x1 - 44, x2 - 44} rev1_2_A(x1,x2) = max{88, x1 - 23} |0|_0_A = 1 nil_0_A = 2 filter_2_A(x1,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: rev1_2#_A(x1,x2) = x2 cons_2_A(x1,x2) = x1 + x2 + 5 rev1_2_A(x1,x2) = x1 + x2 + 5 |0|_0_A() = 1 nil_0_A() = 9 filter_2_A(x1,x2) = x1 + x2 + 14 rev1_2#!_A(x1,x2) = x2 cons_2!_A(x1,x2) = x1 + x2 + 1 rev1_2!_A(x1,x2) = x2 + 17 |0|_0!_A() = 0 nil_0!_A() = 12 filter_2!_A(x1,x2) = 13 partial status: pi(rev1_2#) = [] pi(cons_2) = [] pi(rev1_2) = [] pi(|0|_0) = [] pi(nil_0) = [] pi(filter_2) = [] The following rules are removed: p1 Then no dependency pair remains.