YES We show the termination of the TRS R: +(*(x,y),*(x,z)) -> *(x,+(y,z)) +(+(x,y),z) -> +(x,+(y,z)) +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: +#(*(x,y),*(x,z)) -> +#(y,z) p2: +#(+(x,y),z) -> +#(x,+(y,z)) p3: +#(+(x,y),z) -> +#(y,z) p4: +#(*(x,y),+(*(x,z),u())) -> +#(*(x,+(y,z)),u()) p5: +#(*(x,y),+(*(x,z),u())) -> +#(y,z) and R consists of: r1: +(*(x,y),*(x,z)) -> *(x,+(y,z)) r2: +(+(x,y),z) -> +(x,+(y,z)) r3: +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p5} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: +#(*(x,y),*(x,z)) -> +#(y,z) p2: +#(*(x,y),+(*(x,z),u())) -> +#(y,z) p3: +#(+(x,y),z) -> +#(y,z) p4: +#(+(x,y),z) -> +#(x,+(y,z)) and R consists of: r1: +(*(x,y),*(x,z)) -> *(x,+(y,z)) r2: +(+(x,y),z) -> +(x,+(y,z)) r3: +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: +#_A(x1,x2) = max{x1 + 1, x2 + 1} *_A(x1,x2) = max{x1 + 3, x2 + 3} +_A(x1,x2) = max{x1, x2} u_A = 1 2. max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 *_A(x1,x2) = 0 +_A(x1,x2) = 1 u_A = 0 The next rules are strictly ordered: p1, p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: +#(+(x,y),z) -> +#(y,z) p2: +#(+(x,y),z) -> +#(x,+(y,z)) and R consists of: r1: +(*(x,y),*(x,z)) -> *(x,+(y,z)) r2: +(+(x,y),z) -> +(x,+(y,z)) r3: +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: +#(+(x,y),z) -> +#(y,z) p2: +#(+(x,y),z) -> +#(x,+(y,z)) and R consists of: r1: +(*(x,y),*(x,z)) -> *(x,+(y,z)) r2: +(+(x,y),z) -> +(x,+(y,z)) r3: +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: +#_A(x1,x2) = x1 + 7 +_A(x1,x2) = max{5, x1 + 3, x2} *_A(x1,x2) = x1 + 2 u_A = 4 2. max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 +_A(x1,x2) = 1 *_A(x1,x2) = 0 u_A = 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: +#(+(x,y),z) -> +#(y,z) and R consists of: r1: +(*(x,y),*(x,z)) -> *(x,+(y,z)) r2: +(+(x,y),z) -> +(x,+(y,z)) r3: +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) 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) -> +#(y,z) and R consists of: r1: +(*(x,y),*(x,z)) -> *(x,+(y,z)) r2: +(+(x,y),z) -> +(x,+(y,z)) r3: +(*(x,y),+(*(x,z),u())) -> +(*(x,+(y,z)),u()) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: +#_A(x1,x2) = x1 +_A(x1,x2) = max{x1 + 1, x2 + 1} 2. max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 +_A(x1,x2) = 0 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.