YES We show the termination of the TRS R: f(g(X)) -> g(f(f(X))) f(h(X)) -> h(g(X)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(g(X)) -> f#(f(X)) p2: f#(g(X)) -> f#(X) and R consists of: r1: f(g(X)) -> g(f(f(X))) r2: f(h(X)) -> h(g(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: f#(g(X)) -> f#(f(X)) p2: f#(g(X)) -> f#(X) and R consists of: r1: f(g(X)) -> g(f(f(X))) r2: f(h(X)) -> h(g(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: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = x1 + (4,1) g_A(x1) = ((1,0),(0,0)) x1 + (5,3) f_A(x1) = ((1,0),(1,0)) x1 + (0,1) h_A(x1) = (4,4) precedence: f > g > f# > h partial status: pi(f#) = [1] pi(g) = [] pi(f) = [] pi(h) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = (0,0) g_A(x1) = (0,0) f_A(x1) = (2,2) h_A(x1) = (1,1) precedence: f# > g = f = h partial status: pi(f#) = [] pi(g) = [] pi(f) = [] pi(h) = [] 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: f#(g(X)) -> f#(X) and R consists of: r1: f(g(X)) -> g(f(f(X))) r2: f(h(X)) -> h(g(X)) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(g(X)) -> f#(X) and R consists of: r1: f(g(X)) -> g(f(f(X))) r2: f(h(X)) -> h(g(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: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = ((1,0),(1,1)) x1 + (2,2) g_A(x1) = ((1,0),(0,0)) x1 + (1,1) precedence: f# = g partial status: pi(f#) = [] pi(g) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = ((1,0),(0,0)) x1 g_A(x1) = (1,1) precedence: g > f# partial status: pi(f#) = [] pi(g) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.