YES We show the termination of the TRS R: f(+(x,|0|())) -> f(x) +(x,+(y,z)) -> +(+(x,y),z) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(+(x,|0|())) -> f#(x) p2: +#(x,+(y,z)) -> +#(+(x,y),z) p3: +#(x,+(y,z)) -> +#(x,y) and R consists of: r1: f(+(x,|0|())) -> f(x) r2: +(x,+(y,z)) -> +(+(x,y),z) The estimated dependency graph contains the following SCCs: {p1} {p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(+(x,|0|())) -> f#(x) and R consists of: r1: f(+(x,|0|())) -> f(x) r2: +(x,+(y,z)) -> +(+(x,y),z) 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: f#_A(x1) = max{2, x1 + 1} +_A(x1,x2) = max{x1, x2} |0|_A = 0 precedence: f# = + = |0| partial status: pi(f#) = [1] pi(+) = [1, 2] pi(|0|) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: f#_A(x1) = max{1, x1 - 1} +_A(x1,x2) = x2 |0|_A = 0 precedence: f# = + = |0| partial status: pi(f#) = [] pi(+) = [2] pi(|0|) = [] The next rules are strictly ordered: p1 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: +#(x,+(y,z)) -> +#(+(x,y),z) p2: +#(x,+(y,z)) -> +#(x,y) and R consists of: r1: f(+(x,|0|())) -> f(x) r2: +(x,+(y,z)) -> +(+(x,y),z) The set of usable rules consists of r2 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = x2 + 3 +_A(x1,x2) = max{x1, x2 + 3} precedence: +# = + partial status: pi(+#) = [] pi(+) = [2] 2. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 +_A(x1,x2) = x2 + 2 precedence: +# = + partial status: pi(+#) = [] pi(+) = [2] 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: +#(x,+(y,z)) -> +#(x,y) and R consists of: r1: f(+(x,|0|())) -> f(x) r2: +(x,+(y,z)) -> +(+(x,y),z) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: +#(x,+(y,z)) -> +#(x,y) and R consists of: r1: f(+(x,|0|())) -> f(x) r2: +(x,+(y,z)) -> +(+(x,y),z) 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: +#_A(x1,x2) = max{0, x2 - 2} +_A(x1,x2) = max{x1 + 1, x2 + 3} precedence: +# = + partial status: pi(+#) = [] pi(+) = [1, 2] 2. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 +_A(x1,x2) = max{x1 + 1, x2} precedence: +# = + partial status: pi(+#) = [] pi(+) = [2] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.