YES We show the termination of the TRS R: le(|0|(),y) -> true() le(s(x),|0|()) -> false() le(s(x),s(y)) -> le(x,y) minus(|0|(),y) -> |0|() minus(s(x),y) -> if_minus(le(s(x),y),s(x),y) if_minus(true(),s(x),y) -> |0|() if_minus(false(),s(x),y) -> s(minus(x,y)) mod(|0|(),y) -> |0|() mod(s(x),|0|()) -> |0|() mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) if_mod(false(),s(x),s(y)) -> s(x) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: le#(s(x),s(y)) -> le#(x,y) p2: minus#(s(x),y) -> if_minus#(le(s(x),y),s(x),y) p3: minus#(s(x),y) -> le#(s(x),y) p4: if_minus#(false(),s(x),y) -> minus#(x,y) p5: mod#(s(x),s(y)) -> if_mod#(le(y,x),s(x),s(y)) p6: mod#(s(x),s(y)) -> le#(y,x) p7: if_mod#(true(),s(x),s(y)) -> mod#(minus(x,y),s(y)) p8: if_mod#(true(),s(x),s(y)) -> minus#(x,y) and R consists of: r1: le(|0|(),y) -> true() r2: le(s(x),|0|()) -> false() r3: le(s(x),s(y)) -> le(x,y) r4: minus(|0|(),y) -> |0|() r5: minus(s(x),y) -> if_minus(le(s(x),y),s(x),y) r6: if_minus(true(),s(x),y) -> |0|() r7: if_minus(false(),s(x),y) -> s(minus(x,y)) r8: mod(|0|(),y) -> |0|() r9: mod(s(x),|0|()) -> |0|() r10: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r11: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r12: if_mod(false(),s(x),s(y)) -> s(x) The estimated dependency graph contains the following SCCs: {p5, p7} {p2, p4} {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if_mod#(true(),s(x),s(y)) -> mod#(minus(x,y),s(y)) p2: mod#(s(x),s(y)) -> if_mod#(le(y,x),s(x),s(y)) and R consists of: r1: le(|0|(),y) -> true() r2: le(s(x),|0|()) -> false() r3: le(s(x),s(y)) -> le(x,y) r4: minus(|0|(),y) -> |0|() r5: minus(s(x),y) -> if_minus(le(s(x),y),s(x),y) r6: if_minus(true(),s(x),y) -> |0|() r7: if_minus(false(),s(x),y) -> s(minus(x,y)) r8: mod(|0|(),y) -> |0|() r9: mod(s(x),|0|()) -> |0|() r10: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r11: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r12: if_mod(false(),s(x),s(y)) -> s(x) The set of usable rules consists of r4, r5, r6, r7 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: if_mod#_A(x1,x2,x3) = x3 true_A() = 5 s_A(x1) = 1 mod#_A(x1,x2) = x2 minus_A(x1,x2) = 3 le_A(x1,x2) = x1 + x2 + 1 |0|_A() = 3 if_minus_A(x1,x2,x3) = x2 + 2 false_A() = 6 if_mod#!_A(x1,x2,x3) = 0 true!_A() = 2 s!_A(x1) = 4 mod#!_A(x1,x2) = 1 minus!_A(x1,x2) = 4 le!_A(x1,x2) = x1 + x2 |0|!_A() = 3 if_minus!_A(x1,x2,x3) = 4 false!_A() = 2 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_mod#_A(x1,x2,x3) = max{30, x3 + 2} true_A = 1 s_A(x1) = x1 + 27 mod#_A(x1,x2) = max{30, x2 + 2} minus_A(x1,x2) = x1 + 24 le_A(x1,x2) = x2 + 24 |0|_A = 9 if_minus_A(x1,x2,x3) = x2 + 24 false_A = 3 if_mod#!_A(x1,x2,x3) = max{26, x2 + 6, x3 - 28} true!_A = 1 s!_A(x1) = max{24, x1} mod#!_A(x1,x2) = 25 minus!_A(x1,x2) = max{0, x1 - 1} le!_A(x1,x2) = max{2, x1 - 9} |0|!_A = 9 if_minus!_A(x1,x2,x3) = max{22, x2 - 2} false!_A = 10 partial status: pi(if_mod#) = [2] pi(true) = [] pi(s) = [1] pi(mod#) = [1] pi(minus) = [] pi(le) = [1] pi(|0|) = [] pi(if_minus) = [] pi(false) = [] 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: if_minus#(false(),s(x),y) -> minus#(x,y) p2: minus#(s(x),y) -> if_minus#(le(s(x),y),s(x),y) and R consists of: r1: le(|0|(),y) -> true() r2: le(s(x),|0|()) -> false() r3: le(s(x),s(y)) -> le(x,y) r4: minus(|0|(),y) -> |0|() r5: minus(s(x),y) -> if_minus(le(s(x),y),s(x),y) r6: if_minus(true(),s(x),y) -> |0|() r7: if_minus(false(),s(x),y) -> s(minus(x,y)) r8: mod(|0|(),y) -> |0|() r9: mod(s(x),|0|()) -> |0|() r10: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r11: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r12: if_mod(false(),s(x),s(y)) -> s(x) The set of usable rules consists of r1, r2, r3, r4 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: if_minus#_A(x1,x2,x3) = x2 false_A() = 1 s_A(x1) = x1 + 2 minus#_A(x1,x2) = x1 le_A(x1,x2) = 1 |0|_A() = 3 true_A() = 1 minus_A(x1,x2) = x1 + x2 + 1 if_minus#!_A(x1,x2,x3) = x2 + 2 false!_A() = 2 s!_A(x1) = 2 minus#!_A(x1,x2) = x1 + 3 le!_A(x1,x2) = 2 |0|!_A() = 0 true!_A() = 1 minus!_A(x1,x2) = 2 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_minus#_A(x1,x2,x3) = max{0, x1 - 14, x2 - 15, x3 - 4} false_A = 1 s_A(x1) = max{12, x1 + 2} minus#_A(x1,x2) = max{0, x1 - 13, x2 - 4} le_A(x1,x2) = 12 |0|_A = 0 true_A = 10 minus_A(x1,x2) = max{4, x1 - 4} if_minus#!_A(x1,x2,x3) = max{34, x2 - 10} false!_A = 23 s!_A(x1) = max{33, x1 + 24} minus#!_A(x1,x2) = max{x1 + 33, x2 + 35} le!_A(x1,x2) = max{33, x2 + 22} |0|!_A = 20 true!_A = 21 minus!_A(x1,x2) = 18 partial status: pi(if_minus#) = [] pi(false) = [] pi(s) = [1] pi(minus#) = [] pi(le) = [] pi(|0|) = [] pi(true) = [] pi(minus) = [] 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: le#(s(x),s(y)) -> le#(x,y) and R consists of: r1: le(|0|(),y) -> true() r2: le(s(x),|0|()) -> false() r3: le(s(x),s(y)) -> le(x,y) r4: minus(|0|(),y) -> |0|() r5: minus(s(x),y) -> if_minus(le(s(x),y),s(x),y) r6: if_minus(true(),s(x),y) -> |0|() r7: if_minus(false(),s(x),y) -> s(minus(x,y)) r8: mod(|0|(),y) -> |0|() r9: mod(s(x),|0|()) -> |0|() r10: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r11: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r12: if_mod(false(),s(x),s(y)) -> s(x) 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: le#_A(x1,x2) = x1 + x2 s_A(x1) = x1 + 7 le#!_A(x1,x2) = x1 s!_A(x1) = x1 + 7 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: le#_A(x1,x2) = 0 s_A(x1) = max{14, x1 - 30} le#!_A(x1,x2) = max{0, x1 - 15} s!_A(x1) = max{18, x1 + 4} partial status: pi(le#) = [1] pi(s) = [1] The following rules are removed: p1 Then no dependency pair remains.