YES We show the termination of the TRS R: p(p(b(a(x0)),x1),p(x2,x3)) -> p(p(x3,a(x2)),p(b(a(x1)),b(x0))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(p(x3,a(x2)),p(b(a(x1)),b(x0))) p2: p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(x3,a(x2)) p3: p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(b(a(x1)),b(x0)) and R consists of: r1: p(p(b(a(x0)),x1),p(x2,x3)) -> p(p(x3,a(x2)),p(b(a(x1)),b(x0))) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: p#(p(b(a(x0)),x1),p(x2,x3)) -> p#(p(x3,a(x2)),p(b(a(x1)),b(x0))) and R consists of: r1: p(p(b(a(x0)),x1),p(x2,x3)) -> p(p(x3,a(x2)),p(b(a(x1)),b(x0))) The set of usable rules consists of (no rules) Take the reduction pair: matrix interpretations: carrier: N^2 order: standard order interpretations: p#_A(x1,x2) = ((1,1),(1,0)) x1 + ((0,1),(0,1)) x2 p_A(x1,x2) = ((0,1),(0,0)) x1 + x2 + (0,1) b_A(x1) = ((1,0),(1,0)) x1 a_A(x1) = ((1,1),(0,0)) x1 + (1,0) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.