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: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: if_gcd#_A(x1,x2,x3) = max{21, x2 + 5, x3 + 4} false_A = 1 s_A(x1) = x1 + 14 gcd#_A(x1,x2) = max{20, x1 + 7, x2 + 4} minus_A(x1,x2) = x1 + 4 le_A(x1,x2) = max{7, x1 - 6} true_A = 0 if_minus_A(x1,x2,x3) = max{x1 + 9, x2 + 4} |0|_A = 3 precedence: minus > if_minus > s > le = true > false = |0| > if_gcd# = gcd# partial status: pi(if_gcd#) = [3] pi(false) = [] pi(s) = [1] pi(gcd#) = [2] pi(minus) = [] pi(le) = [] pi(true) = [] pi(if_minus) = [1] pi(|0|) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: if_gcd#_A(x1,x2,x3) = x3 + 13 false_A = 1 s_A(x1) = max{13, x1 - 2} gcd#_A(x1,x2) = x2 + 13 minus_A(x1,x2) = 25 le_A(x1,x2) = 2 true_A = 27 if_minus_A(x1,x2,x3) = max{24, x1 + 1} |0|_A = 26 precedence: minus = le = true > if_gcd# = s = gcd# = if_minus = |0| > false partial status: pi(if_gcd#) = [] pi(false) = [] pi(s) = [] pi(gcd#) = [] pi(minus) = [] pi(le) = [] pi(true) = [] pi(if_minus) = [1] pi(|0|) = [] The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) p2: 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 estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y)) p2: 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: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: gcd#_A(x1,x2) = x1 + 20 s_A(x1) = max{31, x1 + 27} if_gcd#_A(x1,x2,x3) = max{30, x1 + 1, x2 + 1} le_A(x1,x2) = max{45, x2 + 19} true_A = 7 minus_A(x1,x2) = x1 + 7 if_minus_A(x1,x2,x3) = max{38, x2 + 7} |0|_A = 0 false_A = 0 precedence: le = minus > s = true = if_minus = |0| = false > gcd# > if_gcd# partial status: pi(gcd#) = [1] pi(s) = [] pi(if_gcd#) = [1, 2] pi(le) = [2] pi(true) = [] pi(minus) = [1] pi(if_minus) = [2] pi(|0|) = [] pi(false) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: gcd#_A(x1,x2) = x1 + 8 s_A(x1) = 5 if_gcd#_A(x1,x2,x3) = max{4, x1, x2 + 3} le_A(x1,x2) = 13 true_A = 15 minus_A(x1,x2) = 6 if_minus_A(x1,x2,x3) = max{7, x2} |0|_A = 2 false_A = 3 precedence: gcd# = s = if_gcd# = le = true = minus = if_minus = |0| = false partial status: pi(gcd#) = [1] pi(s) = [] pi(if_gcd#) = [] pi(le) = [] pi(true) = [] pi(minus) = [] pi(if_minus) = [2] pi(|0|) = [] pi(false) = [] The next rules are strictly ordered: p1, p2 We remove them from the problem. 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 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: if_minus#_A(x1,x2,x3) = max{x1 + 2, x2 + 1, x3 + 4} false_A = 4 s_A(x1) = x1 + 5 minus#_A(x1,x2) = max{x1 + 6, x2 + 4} le_A(x1,x2) = max{x1 + 3, x2 - 6} |0|_A = 11 true_A = 12 precedence: if_minus# = s = minus# = le = |0| > false = true partial status: pi(if_minus#) = [2] pi(false) = [] pi(s) = [1] pi(minus#) = [1] pi(le) = [] pi(|0|) = [] pi(true) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: if_minus#_A(x1,x2,x3) = max{1, x2} false_A = 7 s_A(x1) = x1 + 8 minus#_A(x1,x2) = x1 le_A(x1,x2) = 1 |0|_A = 0 true_A = 2 precedence: true > if_minus# = false = s = minus# = le = |0| partial status: pi(if_minus#) = [] pi(false) = [] pi(s) = [1] pi(minus#) = [1] pi(le) = [] pi(|0|) = [] pi(true) = [] The next rules are strictly ordered: p1, p2 We remove them from the problem. 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: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: le#_A(x1,x2) = max{2, x1 - 1, x2 + 1} s_A(x1) = max{1, x1} precedence: le# = s partial status: pi(le#) = [2] pi(s) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: le#_A(x1,x2) = 0 s_A(x1) = max{2, x1} precedence: le# = s partial status: pi(le#) = [] pi(s) = [1] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.