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) 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),s(y)) -> minus#(x,y) p3: mod#(s(x),s(y)) -> if_mod#(le(y,x),s(x),s(y)) p4: mod#(s(x),s(y)) -> le#(y,x) p5: if_mod#(true(),s(x),s(y)) -> mod#(minus(x,y),s(y)) p6: 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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: mod(|0|(),y) -> |0|() r7: mod(s(x),|0|()) -> |0|() r8: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r9: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r10: if_mod(false(),s(x),s(y)) -> s(x) The estimated dependency graph contains the following SCCs: {p3, p5} {p1} {p2} -- 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(x,|0|()) -> x r5: minus(s(x),s(y)) -> minus(x,y) r6: mod(|0|(),y) -> |0|() r7: mod(s(x),|0|()) -> |0|() r8: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r9: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r10: if_mod(false(),s(x),s(y)) -> 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_mod#_A(x1,x2,x3) = max{1, x3 - 28} true_A = 59 s_A(x1) = max{27, x1 + 12} mod#_A(x1,x2) = max{1, x2 - 28} minus_A(x1,x2) = x1 + 8 le_A(x1,x2) = x2 + 59 |0|_A = 6 false_A = 1 if_mod#!_A(x1,x2,x3) = max{32, x1 - 25, x2 + 22} true!_A = 1 s!_A(x1) = max{33, x1 + 31} mod#!_A(x1,x2) = x1 + 22 minus!_A(x1,x2) = max{30, x1 - 13} le!_A(x1,x2) = 2 |0|!_A = 30 false!_A = 1 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_mod#_A(x1,x2,x3) = max{1, x3 - 49} true_A = 0 s_A(x1) = max{48, x1 + 13} mod#_A(x1,x2) = max{1, x2 - 49} minus_A(x1,x2) = max{47, x1 + 13, x2 + 13} le_A(x1,x2) = max{33, x1 - 29, x2 - 31} |0|_A = 28 false_A = 5 if_mod#!_A(x1,x2,x3) = max{63, x1 + 30, x2 + 15, x3 + 15} true!_A = 58 s!_A(x1) = 61 mod#!_A(x1,x2) = max{29, x1 + 15, x2 + 15} minus!_A(x1,x2) = max{64, x2 - 49} le!_A(x1,x2) = 59 |0|!_A = 2 false!_A = 3 partial status: pi(if_mod#) = [1, 2] pi(true) = [] pi(s) = [1] pi(mod#) = [1] pi(minus) = [1] pi(le) = [] pi(|0|) = [] 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: 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: mod(|0|(),y) -> |0|() r7: mod(s(x),|0|()) -> |0|() r8: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r9: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r10: if_mod(false(),s(x),s(y)) -> s(x) The set of usable rules consists of r1 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) = max{x1, x2} s_A(x1) = max{8, x1 + 6} le_A(x1,x2) = max{10, x1 - 9, x2 - 5} |0|_A = 2 true_A = 0 le#!_A(x1,x2) = max{4, x1 - 24, x2 - 9} s!_A(x1) = max{3, x1 - 23} le!_A(x1,x2) = max{4, x1 - 9, x2 - 9} |0|!_A = 2 true!_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{3, x1} le_A(x1,x2) = max{2, x1 - 4, x2 - 3} |0|_A = 2 true_A = 0 le#!_A(x1,x2) = max{1, x1 - 10, x2 - 4} s!_A(x1) = max{3, x1 - 9} le!_A(x1,x2) = max{7, x1 - 4, x2 - 4} |0|!_A = 2 true!_A = 6 partial status: pi(le#) = [1] pi(s) = [1] pi(le) = [1] pi(|0|) = [] pi(true) = [] 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: mod(|0|(),y) -> |0|() r7: mod(s(x),|0|()) -> |0|() r8: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r9: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r10: if_mod(false(),s(x),s(y)) -> s(x) The set of usable rules consists of r1 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) = max{x1, x2} s_A(x1) = max{7, x1 + 2} le_A(x1,x2) = max{9, x1 - 8, x2 - 3} |0|_A = 2 true_A = 0 minus#!_A(x1,x2) = max{4, x1 - 8, x2 - 8} s!_A(x1) = max{3, x1 - 26} le!_A(x1,x2) = max{4, x1 - 8, x2 - 8} |0|!_A = 2 true!_A = 1 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{2, x1} le_A(x1,x2) = max{2, x1 - 3, x2 - 3} |0|_A = 2 true_A = 0 minus#!_A(x1,x2) = max{4, x1 - 9, x2 - 10} s!_A(x1) = max{3, x1 - 9} le!_A(x1,x2) = max{5, x1 - 3, x2 - 3} |0|!_A = 2 true!_A = 4 partial status: pi(minus#) = [1] pi(s) = [1] pi(le) = [1] pi(|0|) = [] pi(true) = [] The following rules are removed: p1 Then no dependency pair remains.