YES We show the termination of the TRS R: g(f(x,y),z) -> f(x,g(y,z)) g(h(x,y),z) -> g(x,f(y,z)) g(x,h(y,z)) -> h(g(x,y),z) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: g#(f(x,y),z) -> g#(y,z) p2: g#(h(x,y),z) -> g#(x,f(y,z)) p3: g#(x,h(y,z)) -> g#(x,y) and R consists of: r1: g(f(x,y),z) -> f(x,g(y,z)) r2: g(h(x,y),z) -> g(x,f(y,z)) r3: g(x,h(y,z)) -> h(g(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: g#(f(x,y),z) -> g#(y,z) p2: g#(x,h(y,z)) -> g#(x,y) p3: g#(h(x,y),z) -> g#(x,f(y,z)) and R consists of: r1: g(f(x,y),z) -> f(x,g(y,z)) r2: g(h(x,y),z) -> g(x,f(y,z)) r3: g(x,h(y,z)) -> h(g(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: g#_A(x1,x2) = max{x1 + 2, x2 + 4} f_A(x1,x2) = max{5, x1 - 1, x2} h_A(x1,x2) = max{x1 + 7, x2 + 1} precedence: f > g# = h partial status: pi(g#) = [1, 2] pi(f) = [] pi(h) = [1, 2] 2. weighted path order base order: max/plus interpretations on natural numbers: g#_A(x1,x2) = max{0, x2 - 2} f_A(x1,x2) = 1 h_A(x1,x2) = max{x1 + 1, x2 + 3} precedence: g# = f = h partial status: pi(g#) = [] pi(f) = [] pi(h) = [2] 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: g#(f(x,y),z) -> g#(y,z) p2: g#(h(x,y),z) -> g#(x,f(y,z)) and R consists of: r1: g(f(x,y),z) -> f(x,g(y,z)) r2: g(h(x,y),z) -> g(x,f(y,z)) r3: g(x,h(y,z)) -> h(g(x,y),z) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: g#(f(x,y),z) -> g#(y,z) p2: g#(h(x,y),z) -> g#(x,f(y,z)) and R consists of: r1: g(f(x,y),z) -> f(x,g(y,z)) r2: g(h(x,y),z) -> g(x,f(y,z)) r3: g(x,h(y,z)) -> h(g(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: g#_A(x1,x2) = max{x1 + 1, x2 - 2} f_A(x1,x2) = max{x1 + 2, x2} h_A(x1,x2) = max{x1, x2} precedence: g# = f = h partial status: pi(g#) = [1] pi(f) = [1, 2] pi(h) = [1, 2] 2. weighted path order base order: max/plus interpretations on natural numbers: g#_A(x1,x2) = max{0, x1 - 2} f_A(x1,x2) = max{x1 + 3, x2 + 1} h_A(x1,x2) = max{4, x1 + 1, x2} precedence: g# = f = h partial status: pi(g#) = [] pi(f) = [] pi(h) = [2] The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.