YES We show the termination of the TRS R: *(x,*(y,z)) -> *(*(x,y),z) *(x,x) -> x -- SCC decomposition. 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: *(x,*(y,z)) -> *(*(x,y),z) r2: *(x,x) -> 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: *#(x,*(y,z)) -> *#(*(x,y),z) p2: *#(x,*(y,z)) -> *#(x,y) and R consists of: r1: *(x,*(y,z)) -> *(*(x,y),z) r2: *(x,x) -> x The set of usable rules consists of r1, r2 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: *#_A(x1,x2) = x2 + 4 *_A(x1,x2) = max{x1, x2 + 2} 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. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: *#(x,*(y,z)) -> *#(x,y) and R consists of: r1: *(x,*(y,z)) -> *(*(x,y),z) r2: *(x,x) -> x 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: *(x,*(y,z)) -> *(*(x,y),z) r2: *(x,x) -> x 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) = x2 *_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.