YES We show the termination of R/S, where R is t(f(x),g(y),f(z)) -> t(z,g(x),g(y)) t(g(x),g(y),f(z)) -> t(f(y),f(z),x) and S is: f(g(x)) -> g(f(x)) g(f(x)) -> f(g(x)) f(f(x)) -> g(g(x)) g(g(x)) -> f(f(x)) Since R almost dominates S and S is non-duplicating, it is enough to show finiteness of (P, Q). Here P consists of the dependency pairs t#(f(x),g(y),f(z)) -> t#(z,g(x),g(y)) t#(g(x),g(y),f(z)) -> t#(f(y),f(z),x) and Q consists of the rules: t(f(x),g(y),f(z)) -> t(z,g(x),g(y)) t(g(x),g(y),f(z)) -> t(f(y),f(z),x) f(g(x)) -> g(f(x)) g(f(x)) -> f(g(x)) f(f(x)) -> g(g(x)) g(g(x)) -> f(f(x)) The weakly monotone algebra (N^2, >_lex) with t#_A((x1,y1),(x2,y2),(x3,y3)) = (x1 + x2 + x3, y1 + y3) f_A((x1,y1)) = (x1 + 1, 1) g_A((x1,y1)) = (x1 + 1, 1) t_A((x1,y1),(x2,y2),(x3,y3)) = (x1 + x2 + x3, y2) strictly orients the following dependency pairs: t#(f(x),g(y),f(z)) -> t#(z,g(x),g(y)) t#(g(x),g(y),f(z)) -> t#(f(y),f(z),x) We remove them from the set of dependency pairs. No dependency pair remains.