YES We show the termination of the TRS R: w(r(x)) -> r(w(x)) b(r(x)) -> r(b(x)) b(w(x)) -> w(b(x)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: w#(r(x)) -> w#(x) p2: b#(r(x)) -> b#(x) p3: b#(w(x)) -> w#(b(x)) p4: b#(w(x)) -> b#(x) and R consists of: r1: w(r(x)) -> r(w(x)) r2: b(r(x)) -> r(b(x)) r3: b(w(x)) -> w(b(x)) The estimated dependency graph contains the following SCCs: {p2, p4} {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(w(x)) -> b#(x) p2: b#(r(x)) -> b#(x) and R consists of: r1: w(r(x)) -> r(w(x)) r2: b(r(x)) -> r(b(x)) r3: b(w(x)) -> w(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: b#_A(x1) = ((1,1),(1,1)) x1 w_A(x1) = ((1,1),(1,1)) x1 + (1,1) r_A(x1) = ((1,1),(1,1)) x1 + (1,1) 2. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1) = ((0,1),(1,1)) x1 w_A(x1) = x1 + (1,1) r_A(x1) = ((0,1),(1,1)) x1 + (1,1) The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: w#(r(x)) -> w#(x) and R consists of: r1: w(r(x)) -> r(w(x)) r2: b(r(x)) -> r(b(x)) r3: b(w(x)) -> w(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: w#_A(x1) = ((1,1),(1,1)) x1 r_A(x1) = ((1,1),(1,1)) x1 + (1,1) 2. matrix interpretations: carrier: N^2 order: standard order interpretations: w#_A(x1) = ((0,1),(1,1)) x1 r_A(x1) = ((1,0),(1,1)) x1 + (1,1) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.