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: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: p#_A(x1,x2) = ((1,0),(0,0)) x1 + ((0,1),(0,0)) x2 + (7,2) p_A(x1,x2) = ((1,0),(0,0)) x1 + ((1,0),(1,0)) x2 + (5,0) b_A(x1) = ((1,1),(0,0)) x1 + (6,3) a_A(x1) = ((0,0),(1,1)) x1 + (4,1) precedence: p# = p = b = a partial status: pi(p#) = [] pi(p) = [] pi(b) = [] pi(a) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: p#_A(x1,x2) = x1 p_A(x1,x2) = ((1,1),(0,0)) x1 + ((1,0),(1,0)) x2 + (5,0) b_A(x1) = ((0,1),(0,0)) x1 + (0,1) a_A(x1) = (4,2) precedence: p# = p = b = a partial status: pi(p#) = [1] pi(p) = [] pi(b) = [] pi(a) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.