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. weighted path order base order: max/plus interpretations on natural numbers: *#_A(x1,x2) = max{0, x2 - 4} *_A(x1,x2) = max{5, 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(*) = [] 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. 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.