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)) gcd(|0|(),y) -> y gcd(s(x),|0|()) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),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: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) p6: gcd#(s(x),s(y)) -> le#(y,x) p7: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) p8: if_gcd#(true(),s(x),s(y)) -> minus#(x,y) p9: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) p10: if_gcd#(false(),s(x),s(y)) -> minus#(y,x) 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: gcd(|0|(),y) -> y r9: gcd(s(x),|0|()) -> s(x) r10: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r11: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r12: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) The estimated dependency graph contains the following SCCs: {p5, p7, p9} {p2, p4} {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) p2: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) p3: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),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: gcd(|0|(),y) -> y r9: gcd(s(x),|0|()) -> s(x) r10: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r11: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r12: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) The set of usable rules consists of r1, r2, r3, 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_gcd#_A(x1,x2,x3) = x2 + x3 false_A() = 1 s_A(x1) = x1 + 7 gcd#_A(x1,x2) = x1 + x2 minus_A(x1,x2) = x1 + 5 le_A(x1,x2) = x2 + 1 true_A() = 1 |0|_A() = 12 if_minus_A(x1,x2,x3) = x2 + 5 if_gcd#!_A(x1,x2,x3) = x2 + x3 false!_A() = 26 s!_A(x1) = 25 gcd#!_A(x1,x2) = x1 + x2 + 1 minus!_A(x1,x2) = x1 + x2 + 17 le!_A(x1,x2) = x1 + x2 + 16 true!_A() = 27 |0|!_A() = 27 if_minus!_A(x1,x2,x3) = 18 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_gcd#_A(x1,x2,x3) = max{28, x1 - 45, x2 + 1, x3} false_A = 46 s_A(x1) = x1 + 21 gcd#_A(x1,x2) = max{16, x1 + 10, x2} minus_A(x1,x2) = x1 + 11 le_A(x1,x2) = max{x1 + 24, x2 + 60} true_A = 60 |0|_A = 0 if_minus_A(x1,x2,x3) = x2 + 11 if_gcd#!_A(x1,x2,x3) = max{52, x2 + 39, x3 + 33} false!_A = 7 s!_A(x1) = 2 gcd#!_A(x1,x2) = max{x1 + 40, x2 + 34} minus!_A(x1,x2) = max{22, x1, x2 + 9} le!_A(x1,x2) = max{x1 - 7, x2 + 8} true!_A = 5 |0|!_A = 5 if_minus!_A(x1,x2,x3) = max{23, x1 + 22, x3 + 21} partial status: pi(if_gcd#) = [] pi(false) = [] pi(s) = [] pi(gcd#) = [] pi(minus) = [2] pi(le) = [] pi(true) = [] pi(|0|) = [] pi(if_minus) = [1] 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: 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: gcd(|0|(),y) -> y r9: gcd(s(x),|0|()) -> s(x) r10: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r11: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r12: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),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) = x1 + 1 |0|_A() = 4 true_A() = 1 minus_A(x1,x2) = x1 + x2 + 2 if_minus#!_A(x1,x2,x3) = 4 false!_A() = 3 s!_A(x1) = x1 + 2 minus#!_A(x1,x2) = 4 le!_A(x1,x2) = 6 |0|!_A() = 0 true!_A() = 1 minus!_A(x1,x2) = 5 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_minus#_A(x1,x2,x3) = max{0, x1 - 16, x2 - 36, x3 - 10} false_A = 0 s_A(x1) = x1 + 34 minus#_A(x1,x2) = max{0, x1 - 36, x2 - 10} le_A(x1,x2) = max{15, x1 - 35, x2 - 8} |0|_A = 1 true_A = 6 minus_A(x1,x2) = max{50, x1 - 59, x2 - 59} if_minus#!_A(x1,x2,x3) = max{14, x2 - 22} false!_A = 24 s!_A(x1) = x1 + 4 minus#!_A(x1,x2) = max{13, x1 - 12} le!_A(x1,x2) = max{23, x1 - 2, x2 - 2} |0|!_A = 1 true!_A = 24 minus!_A(x1,x2) = max{7, x1 + 5, x2 - 63} partial status: pi(if_minus#) = [] pi(false) = [] pi(s) = [1] pi(minus#) = [] pi(le) = [1] pi(|0|) = [] pi(true) = [] pi(minus) = [1] 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: gcd(|0|(),y) -> y r9: gcd(s(x),|0|()) -> s(x) r10: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r11: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r12: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),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 s_A(x1) = x1 + 5 le#!_A(x1,x2) = x1 + x2 s!_A(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{11, x1 - 21} le#!_A(x1,x2) = max{29, x2 - 12} s!_A(x1) = x1 + 28 partial status: pi(le#) = [] pi(s) = [] The following rules are removed: p1 Then no dependency pair remains.