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(x,|0|()) -> x minus(s(x),s(y)) -> 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),s(y)) -> minus#(x,y) p3: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) p4: gcd#(s(x),s(y)) -> le#(y,x) p5: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y)) p6: if_gcd#(true(),s(x),s(y)) -> minus#(x,y) p7: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x)) p8: 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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: gcd(|0|(),y) -> y r7: gcd(s(x),|0|()) -> s(x) r8: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r9: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r10: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) The estimated dependency graph contains the following SCCs: {p3, p5, p7} {p1} {p2} -- 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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: gcd(|0|(),y) -> y r7: gcd(s(x),|0|()) -> s(x) r8: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r9: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r10: 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 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: if_gcd#_A(x1,x2,x3) = max{0, x1 - 7, x2 - 56, x3 - 57} false_A = 6 s_A(x1) = max{45, x1 + 29} gcd#_A(x1,x2) = max{0, x1 - 53, x2 - 57} minus_A(x1,x2) = max{43, x1 + 7, x2 - 30} le_A(x1,x2) = max{0, x1 - 39, x2 - 39} true_A = 0 |0|_A = 38 if_gcd#!_A(x1,x2,x3) = max{x1 + 21, x2 - 26, x3 - 46} false!_A = 2 s!_A(x1) = 29 gcd#!_A(x1,x2) = max{21, x1 - 25, x2 - 46} minus!_A(x1,x2) = 28 le!_A(x1,x2) = max{3, x1 - 46, x2 - 46} true!_A = 2 |0|!_A = 3 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_gcd#_A(x1,x2,x3) = max{0, x1 - 29, x2 - 49, x3 - 50} false_A = 20 s_A(x1) = max{46, x1 + 28} gcd#_A(x1,x2) = max{0, x1 - 47, x2 - 50} minus_A(x1,x2) = max{45, x1 + 1} le_A(x1,x2) = max{19, x1 - 27, x2 - 29} true_A = 24 |0|_A = 57 if_gcd#!_A(x1,x2,x3) = max{9, x2 - 21} false!_A = 4 s!_A(x1) = x1 + 6 gcd#!_A(x1,x2) = max{25, x1 - 20} minus!_A(x1,x2) = max{6, x1 - 47} le!_A(x1,x2) = max{5, x1 - 68, x2 - 65} true!_A = 2 |0|!_A = 3 partial status: pi(if_gcd#) = [1] pi(false) = [] pi(s) = [1] pi(gcd#) = [] pi(minus) = [1] pi(le) = [] pi(true) = [] pi(|0|) = [] The following rules are removed: p1, p2 -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: 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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: gcd(|0|(),y) -> y r7: gcd(s(x),|0|()) -> s(x) r8: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r9: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r10: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) The estimated dependency graph contains the following SCCs: (no SCCs) -- 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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: gcd(|0|(),y) -> y r7: gcd(s(x),|0|()) -> s(x) r8: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r9: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r10: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) The set of usable rules consists of r1, r2 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: le#_A(x1,x2) = 0 s_A(x1) = max{3, x1 - 11} le_A(x1,x2) = max{7, x1 - 4, x2 - 4} |0|_A = 3 true_A = 0 false_A = 0 le#!_A(x1,x2) = 0 s!_A(x1) = 2 le!_A(x1,x2) = max{3, x1 - 16, x2 - 21} |0|!_A = 2 true!_A = 1 false!_A = 1 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: le#_A(x1,x2) = max{x1, x2} s_A(x1) = max{14, x1 + 6} le_A(x1,x2) = max{16, x1 - 15, x2 - 15} |0|_A = 14 true_A = 0 false_A = 0 le#!_A(x1,x2) = max{1, x1 - 12, x2 - 15} s!_A(x1) = 2 le!_A(x1,x2) = max{4, x1 - 15, x2 - 15} |0|!_A = 2 true!_A = 3 false!_A = 10 partial status: pi(le#) = [] pi(s) = [] pi(le) = [] pi(|0|) = [] pi(true) = [] pi(false) = [] 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: minus#(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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: gcd(|0|(),y) -> y r7: gcd(s(x),|0|()) -> s(x) r8: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) r9: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y)) r10: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x)) The set of usable rules consists of r1, r2 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: minus#_A(x1,x2) = 0 s_A(x1) = max{3, x1 - 20} le_A(x1,x2) = max{16, x1 - 4, x2 - 4} |0|_A = 3 true_A = 7 false_A = 0 minus#!_A(x1,x2) = 0 s!_A(x1) = 7 le!_A(x1,x2) = max{1, x1 - 31, x2 - 31} |0|!_A = 6 true!_A = 5 false!_A = 3 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: minus#_A(x1,x2) = max{x1, x2} s_A(x1) = max{7, x1 + 1} le_A(x1,x2) = max{2, x1 - 8, x2 - 1} |0|_A = 0 true_A = 0 false_A = 0 minus#!_A(x1,x2) = max{4, x1 - 2, x2 - 8} s!_A(x1) = 3 le!_A(x1,x2) = max{1, x1 - 8, x2 - 10} |0|!_A = 5 true!_A = 4 false!_A = 7 partial status: pi(minus#) = [] pi(s) = [1] pi(le) = [1] pi(|0|) = [] pi(true) = [] pi(false) = [] The following rules are removed: p1 Then no dependency pair remains.