(VAR x y ) (RULES f(x,a(b(y))) -> f(a(b(x)),y) f(x,b(c(y))) -> f(b(c(x)),y) f(x,c(a(y))) -> f(c(a(x)),y) f(a(x),y) -> f(x,a(y)) f(b(x),y) -> f(x,b(y)) f(c(x),y) -> f(x,c(y)) ) (COMMENT: TRS variant of simply terminating SRS ab -> ba, bc -> cb, ca -> ac )