YES We show the termination of the TRS R: a(b(x)) -> b(a(a(x))) b(c(x)) -> c(b(b(x))) c(a(x)) -> a(c(c(x))) u(a(x)) -> x v(b(x)) -> x w(c(x)) -> x a(u(x)) -> x b(v(x)) -> x c(w(x)) -> x -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a#(b(x)) -> b#(a(a(x))) p2: a#(b(x)) -> a#(a(x)) p3: a#(b(x)) -> a#(x) p4: b#(c(x)) -> c#(b(b(x))) p5: b#(c(x)) -> b#(b(x)) p6: b#(c(x)) -> b#(x) p7: c#(a(x)) -> a#(c(c(x))) p8: c#(a(x)) -> c#(c(x)) p9: c#(a(x)) -> c#(x) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5, p6, p7, p8, p9} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a#(b(x)) -> b#(a(a(x))) p2: b#(c(x)) -> b#(x) p3: b#(c(x)) -> b#(b(x)) p4: b#(c(x)) -> c#(b(b(x))) p5: c#(a(x)) -> c#(x) p6: c#(a(x)) -> c#(c(x)) p7: c#(a(x)) -> a#(c(c(x))) p8: a#(b(x)) -> a#(x) p9: a#(b(x)) -> a#(a(x)) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The set of usable rules consists of r1, r2, r3, r7, r8, r9 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = ((1,0),(1,0)) x1 + (0,4) b_A(x1) = ((1,0),(0,0)) x1 + (0,1) b#_A(x1) = ((1,0),(0,0)) x1 + (0,3) a_A(x1) = ((1,0),(1,1)) x1 + (0,5) c_A(x1) = x1 c#_A(x1) = x1 + (0,1) u_A(x1) = x1 + (1,1) v_A(x1) = ((1,0),(1,1)) x1 + (1,1) w_A(x1) = x1 + (1,1) precedence: a# = b > c > a > v > b# = u = w > c# partial status: pi(a#) = [] pi(b) = [] pi(b#) = [] pi(a) = [] pi(c) = [] pi(c#) = [1] pi(u) = [] pi(v) = [1] pi(w) = [1] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = (3,3) b_A(x1) = (1,1) b#_A(x1) = (2,2) a_A(x1) = (1,1) c_A(x1) = (1,1) c#_A(x1) = ((1,0),(1,0)) x1 + (3,3) u_A(x1) = (1,1) v_A(x1) = x1 + (1,1) w_A(x1) = x1 + (1,1) precedence: w > u > v > b = a = c > c# > a# > b# partial status: pi(a#) = [] pi(b) = [] pi(b#) = [] pi(a) = [] pi(c) = [] pi(c#) = [] pi(u) = [] pi(v) = [] pi(w) = [] The next rules are strictly ordered: p1, p4, p5, p7 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: b#(c(x)) -> b#(x) p2: b#(c(x)) -> b#(b(x)) p3: c#(a(x)) -> c#(c(x)) p4: a#(b(x)) -> a#(x) p5: a#(b(x)) -> a#(a(x)) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The estimated dependency graph contains the following SCCs: {p1, p2} {p3} {p4, p5} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(c(x)) -> b#(x) p2: b#(c(x)) -> b#(b(x)) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The set of usable rules consists of r1, r2, r3, r7, r8, r9 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: b#_A(x1) = x1 + (1,3) c_A(x1) = ((1,0),(1,1)) x1 + (0,2) b_A(x1) = x1 a_A(x1) = ((1,0),(0,0)) x1 + (0,1) u_A(x1) = x1 + (1,1) w_A(x1) = x1 + (1,0) v_A(x1) = x1 + (1,1) precedence: b# = c = b = a = u = w = v partial status: pi(b#) = [] pi(c) = [] pi(b) = [] pi(a) = [] pi(u) = [] pi(w) = [] pi(v) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: b#_A(x1) = ((1,0),(1,0)) x1 + (1,2) c_A(x1) = ((1,0),(0,0)) x1 + (2,1) b_A(x1) = ((1,0),(0,0)) x1 + (0,2) a_A(x1) = (5,3) u_A(x1) = x1 + (1,1) w_A(x1) = ((1,0),(0,0)) x1 + (1,1) v_A(x1) = x1 + (1,1) precedence: a = u = v > w > b > b# > c partial status: pi(b#) = [] pi(c) = [] pi(b) = [] pi(a) = [] pi(u) = [] pi(w) = [] pi(v) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: b#(c(x)) -> b#(x) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(c(x)) -> b#(x) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x 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: lexicographic order interpretations: b#_A(x1) = ((1,0),(1,1)) x1 + (2,2) c_A(x1) = ((1,0),(0,0)) x1 + (1,1) precedence: b# = c partial status: pi(b#) = [] pi(c) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: b#_A(x1) = ((1,0),(0,0)) x1 c_A(x1) = (1,1) precedence: c > b# partial status: pi(b#) = [] pi(c) = [] The next rules are strictly ordered: p1 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: c#(a(x)) -> c#(c(x)) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The set of usable rules consists of r1, r2, r3, r7, r8, r9 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: c#_A(x1) = x1 + (0,1) a_A(x1) = x1 + (0,2) c_A(x1) = x1 b_A(x1) = ((1,0),(0,0)) x1 + (0,1) v_A(x1) = ((1,0),(1,1)) x1 + (1,1) u_A(x1) = ((1,0),(1,1)) x1 + (1,1) w_A(x1) = x1 + (1,1) precedence: b > c# = c > a > v = u = w partial status: pi(c#) = [1] pi(a) = [] pi(c) = [] pi(b) = [] pi(v) = [1] pi(u) = [1] pi(w) = [1] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: c#_A(x1) = ((1,0),(0,0)) x1 + (0,3) a_A(x1) = (2,1) c_A(x1) = (1,2) b_A(x1) = (1,2) v_A(x1) = (0,1) u_A(x1) = x1 + (1,1) w_A(x1) = x1 + (1,1) precedence: w > u > v > c# = a > b > c partial status: pi(c#) = [] pi(a) = [] pi(c) = [] pi(b) = [] pi(v) = [] pi(u) = [] pi(w) = [] The next rules are strictly ordered: p1 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: a#(b(x)) -> a#(x) p2: a#(b(x)) -> a#(a(x)) and R consists of: r1: a(b(x)) -> b(a(a(x))) r2: b(c(x)) -> c(b(b(x))) r3: c(a(x)) -> a(c(c(x))) r4: u(a(x)) -> x r5: v(b(x)) -> x r6: w(c(x)) -> x r7: a(u(x)) -> x r8: b(v(x)) -> x r9: c(w(x)) -> x The set of usable rules consists of r1, r2, r3, r7, r8, r9 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = x1 b_A(x1) = x1 + (0,2) a_A(x1) = x1 c_A(x1) = ((1,0),(0,0)) x1 + (0,1) w_A(x1) = x1 + (1,1) v_A(x1) = ((1,0),(0,0)) x1 + (1,1) u_A(x1) = x1 + (0,1) precedence: c > a > a# = b = v = u > w partial status: pi(a#) = [1] pi(b) = [1] pi(a) = [] pi(c) = [] pi(w) = [1] pi(v) = [] pi(u) = [1] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = ((1,0),(0,0)) x1 b_A(x1) = ((1,0),(0,0)) x1 + (2,0) a_A(x1) = (1,1) c_A(x1) = (3,0) w_A(x1) = x1 + (0,1) v_A(x1) = (0,1) u_A(x1) = x1 + (1,1) precedence: a# = b = a > u > c > w > v partial status: pi(a#) = [] pi(b) = [] pi(a) = [] pi(c) = [] pi(w) = [1] pi(v) = [] pi(u) = [] The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.