YES We show the termination of the TRS R: a(b(a(x))) -> b(a(b(x))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a#(b(a(x))) -> a#(b(x)) and R consists of: r1: a(b(a(x))) -> b(a(b(x))) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a#(b(a(x))) -> a#(b(x)) and R consists of: r1: a(b(a(x))) -> b(a(b(x))) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. matrix interpretations: carrier: N^2 order: standard order interpretations: a#_A(x1) = x1 b_A(x1) = ((1,0),(1,1)) x1 + (1,1) a_A(x1) = ((1,1),(1,1)) x1 + (1,1) 2. matrix interpretations: carrier: N^2 order: standard order interpretations: a#_A(x1) = ((0,1),(1,0)) x1 b_A(x1) = ((0,0),(1,1)) x1 + (1,1) a_A(x1) = ((0,1),(0,1)) x1 + (1,0) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.