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) pred(s(x)) -> x minus(x,|0|()) -> x minus(x,s(y)) -> pred(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#(x,s(y)) -> pred#(minus(x,y)) p3: minus#(x,s(y)) -> minus#(x,y) p4: mod#(s(x),s(y)) -> if_mod#(le(y,x),s(x),s(y)) p5: mod#(s(x),s(y)) -> le#(y,x) p6: if_mod#(true(),s(x),s(y)) -> mod#(minus(x,y),s(y)) p7: 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: pred(s(x)) -> x r5: minus(x,|0|()) -> x r6: minus(x,s(y)) -> pred(minus(x,y)) r7: mod(|0|(),y) -> |0|() r8: mod(s(x),|0|()) -> |0|() r9: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r10: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r11: if_mod(false(),s(x),s(y)) -> s(x) The estimated dependency graph contains the following SCCs: {p4, p6} {p1} {p3} -- 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: pred(s(x)) -> x r5: minus(x,|0|()) -> x r6: minus(x,s(y)) -> pred(minus(x,y)) r7: mod(|0|(),y) -> |0|() r8: mod(s(x),|0|()) -> |0|() r9: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r10: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r11: if_mod(false(),s(x),s(y)) -> s(x) The set of usable rules consists of r1, r2, r3, r4, r5, r6 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: if_mod#_A(x1,x2,x3) = max{8, x2 - 3, x3 - 7} true_A = 5 s_A(x1) = x1 + 12 mod#_A(x1,x2) = max{2, x1 - 3, x2 - 7} minus_A(x1,x2) = max{9, x1 + 2, x2 + 4} le_A(x1,x2) = max{8, x1 + 6, x2 + 4} |0|_A = 6 false_A = 0 pred_A(x1) = max{15, x1 - 10} base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: if_mod#_A(x1,x2,x3) = max{0, x1 - 20, x2 - 38, x3 - 32} true_A = 0 s_A(x1) = max{30, x1 + 23} mod#_A(x1,x2) = max{0, x1 - 33, x2 - 32} minus_A(x1,x2) = max{19, x1 + 1} le_A(x1,x2) = max{19, x1 - 31, x2 - 51} |0|_A = 9 false_A = 0 pred_A(x1) = max{2, x1 - 20} if_mod#!_A(x1,x2,x3) = max{11, x2 - 10} true!_A = 2 s!_A(x1) = 12 mod#!_A(x1,x2) = max{12, x1 - 2} minus!_A(x1,x2) = 12 le!_A(x1,x2) = max{10, x1 + 1, x2 + 1} |0|!_A = 12 false!_A = 11 pred!_A(x1) = max{11, x1 - 21} partial status: pi(if_mod#) = [] pi(true) = [] pi(s) = [1] pi(mod#) = [] pi(minus) = [] pi(le) = [1] pi(|0|) = [] pi(false) = [] pi(pred) = [] 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: pred(s(x)) -> x r5: minus(x,|0|()) -> x r6: minus(x,s(y)) -> pred(minus(x,y)) r7: mod(|0|(),y) -> |0|() r8: mod(s(x),|0|()) -> |0|() r9: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r10: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r11: 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: max/plus interpretation on natural numbers: le#_A(x1,x2) = 0 s_A(x1) = max{3, x1 - 10} le_A(x1,x2) = max{4, x1 - 20, x2 - 19} |0|_A = 2 true_A = 1 base order 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{12, x1 + 1} le_A(x1,x2) = max{8, x1 - 13, x2 - 3} |0|_A = 2 true_A = 0 le#!_A(x1,x2) = max{4, x1 - 2, x2 - 13} s!_A(x1) = max{3, x1 - 46} le!_A(x1,x2) = max{2, x1 - 25, x2 - 43} |0|!_A = 2 true!_A = 1 partial status: pi(le#) = [] pi(s) = [] pi(le) = [] 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#(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: pred(s(x)) -> x r5: minus(x,|0|()) -> x r6: minus(x,s(y)) -> pred(minus(x,y)) r7: mod(|0|(),y) -> |0|() r8: mod(s(x),|0|()) -> |0|() r9: mod(s(x),s(y)) -> if_mod(le(y,x),s(x),s(y)) r10: if_mod(true(),s(x),s(y)) -> mod(minus(x,y),s(y)) r11: 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: max/plus interpretation on natural numbers: minus#_A(x1,x2) = x1 + 5 s_A(x1) = max{3, x1 - 16} le_A(x1,x2) = max{x1 - 17, x2 + 15} |0|_A = 2 true_A = 1 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: minus#_A(x1,x2) = x2 s_A(x1) = x1 + 12 le_A(x1,x2) = max{13, x1 - 16, x2 - 16} |0|_A = 15 true_A = 0 minus#!_A(x1,x2) = max{9, x2 - 2} s!_A(x1) = max{8, x1 - 78} le!_A(x1,x2) = max{9, x1 - 10, x2 - 13} |0|!_A = 7 true!_A = 6 partial status: pi(minus#) = [1] pi(s) = [] pi(le) = [2] pi(|0|) = [] pi(true) = [] The following rules are removed: p1 Then no dependency pair remains.