YES We show the termination of the TRS R: f(a()) -> b() f(c()) -> d() f(g(x,y)) -> g(f(x),f(y)) f(h(x,y)) -> g(h(y,f(x)),h(x,f(y))) g(x,x) -> h(e(),x) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(g(x,y)) -> g#(f(x),f(y)) p2: f#(g(x,y)) -> f#(x) p3: f#(g(x,y)) -> f#(y) p4: f#(h(x,y)) -> g#(h(y,f(x)),h(x,f(y))) p5: f#(h(x,y)) -> f#(x) p6: f#(h(x,y)) -> f#(y) and R consists of: r1: f(a()) -> b() r2: f(c()) -> d() r3: f(g(x,y)) -> g(f(x),f(y)) r4: f(h(x,y)) -> g(h(y,f(x)),h(x,f(y))) r5: g(x,x) -> h(e(),x) The estimated dependency graph contains the following SCCs: {p2, p3, p5, p6} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(g(x,y)) -> f#(x) p2: f#(h(x,y)) -> f#(y) p3: f#(h(x,y)) -> f#(x) p4: f#(g(x,y)) -> f#(y) and R consists of: r1: f(a()) -> b() r2: f(c()) -> d() r3: f(g(x,y)) -> g(f(x),f(y)) r4: f(h(x,y)) -> g(h(y,f(x)),h(x,f(y))) r5: g(x,x) -> h(e(),x) The set of usable rules consists of (no rules) Take the monotone reduction pair: lexicographic combination of reduction pairs: 1. matrix interpretations: carrier: N^1 order: standard order interpretations: f#_A(x1) = x1 g_A(x1,x2) = x1 + x2 + 1 h_A(x1,x2) = x1 + x2 + 1 2. matrix interpretations: carrier: N^1 order: standard order interpretations: f#_A(x1) = x1 g_A(x1,x2) = x1 + x2 + 1 h_A(x1,x2) = x1 + x2 + 1 The next rules are strictly ordered: p1, p2, p3, p4 r1, r2, r3, r4, r5 We remove them from the problem. Then no dependency pair remains.