YES We show the termination of the TRS R: times(x,plus(y,s(z))) -> plus(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) times(x,|0|()) -> |0|() times(x,s(y)) -> plus(times(x,y),x) plus(x,|0|()) -> x plus(x,s(y)) -> s(plus(x,y)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: times#(x,plus(y,s(z))) -> plus#(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) p2: times#(x,plus(y,s(z))) -> times#(x,plus(y,times(s(z),|0|()))) p3: times#(x,plus(y,s(z))) -> plus#(y,times(s(z),|0|())) p4: times#(x,plus(y,s(z))) -> times#(s(z),|0|()) p5: times#(x,plus(y,s(z))) -> times#(x,s(z)) p6: times#(x,s(y)) -> plus#(times(x,y),x) p7: times#(x,s(y)) -> times#(x,y) p8: plus#(x,s(y)) -> plus#(x,y) and R consists of: r1: times(x,plus(y,s(z))) -> plus(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) r2: times(x,|0|()) -> |0|() r3: times(x,s(y)) -> plus(times(x,y),x) r4: plus(x,|0|()) -> x r5: plus(x,s(y)) -> s(plus(x,y)) The estimated dependency graph contains the following SCCs: {p2, p5, p7} {p8} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: times#(x,s(y)) -> times#(x,y) p2: times#(x,plus(y,s(z))) -> times#(x,s(z)) p3: times#(x,plus(y,s(z))) -> times#(x,plus(y,times(s(z),|0|()))) and R consists of: r1: times(x,plus(y,s(z))) -> plus(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) r2: times(x,|0|()) -> |0|() r3: times(x,s(y)) -> plus(times(x,y),x) r4: plus(x,|0|()) -> x r5: plus(x,s(y)) -> s(plus(x,y)) The set of usable rules consists of r2, r4, r5 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: times#_A(x1,x2) = max{1, x2 - 6} s_A(x1) = max{5, x1} plus_A(x1,x2) = max{14, x1 + 8, x2 + 4} times_A(x1,x2) = max{x1, x2 + 10} |0|_A = 0 precedence: times# = plus > s > times = |0| partial status: pi(times#) = [] pi(s) = [1] pi(plus) = [2] pi(times) = [1, 2] pi(|0|) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: times#_A(x1,x2) = 0 s_A(x1) = x1 + 15 plus_A(x1,x2) = max{5, x2 - 4} times_A(x1,x2) = max{x1 + 15, x2 + 2} |0|_A = 14 precedence: s = times = |0| > plus > times# partial status: pi(times#) = [] pi(s) = [1] pi(plus) = [] pi(times) = [1, 2] pi(|0|) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: times#(x,s(y)) -> times#(x,y) p2: times#(x,plus(y,s(z))) -> times#(x,plus(y,times(s(z),|0|()))) and R consists of: r1: times(x,plus(y,s(z))) -> plus(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) r2: times(x,|0|()) -> |0|() r3: times(x,s(y)) -> plus(times(x,y),x) r4: plus(x,|0|()) -> x r5: plus(x,s(y)) -> s(plus(x,y)) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: times#(x,s(y)) -> times#(x,y) p2: times#(x,plus(y,s(z))) -> times#(x,plus(y,times(s(z),|0|()))) and R consists of: r1: times(x,plus(y,s(z))) -> plus(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) r2: times(x,|0|()) -> |0|() r3: times(x,s(y)) -> plus(times(x,y),x) r4: plus(x,|0|()) -> x r5: plus(x,s(y)) -> s(plus(x,y)) The set of usable rules consists of r2, r4, r5 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: times#_A(x1,x2) = max{x1 + 13, x2 + 4} s_A(x1) = max{6, x1} plus_A(x1,x2) = max{x1 + 14, x2 + 7} times_A(x1,x2) = max{x1, x2 + 6} |0|_A = 0 precedence: times# = plus > s > times = |0| partial status: pi(times#) = [2] pi(s) = [1] pi(plus) = [2] pi(times) = [2] pi(|0|) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: times#_A(x1,x2) = x2 + 3 s_A(x1) = max{12, x1 + 8} plus_A(x1,x2) = max{5, x2} times_A(x1,x2) = max{6, x2} |0|_A = 7 precedence: times# = s = plus = times = |0| partial status: pi(times#) = [] pi(s) = [] pi(plus) = [2] pi(times) = [2] pi(|0|) = [] 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: plus#(x,s(y)) -> plus#(x,y) and R consists of: r1: times(x,plus(y,s(z))) -> plus(times(x,plus(y,times(s(z),|0|()))),times(x,s(z))) r2: times(x,|0|()) -> |0|() r3: times(x,s(y)) -> plus(times(x,y),x) r4: plus(x,|0|()) -> x r5: plus(x,s(y)) -> s(plus(x,y)) 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: plus#_A(x1,x2) = max{2, x1, x2 + 1} s_A(x1) = max{1, x1} precedence: plus# = s partial status: pi(plus#) = [1, 2] pi(s) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: plus#_A(x1,x2) = max{x1, x2 - 1} s_A(x1) = x1 precedence: plus# = s partial status: pi(plus#) = [1] pi(s) = [1] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.