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: max/plus interpretations on natural numbers: a#_A(x1) = x1 + 1 b_A(x1) = x1 b#_A(x1) = x1 + 1 a_A(x1) = x1 c_A(x1) = x1 c#_A(x1) = x1 + 1 u_A(x1) = x1 + 1 v_A(x1) = x1 + 1 w_A(x1) = x1 + 1 precedence: a# = b = b# = a = c = c# = u = v = w partial status: pi(a#) = [] pi(b) = [] pi(b#) = [] pi(a) = [] pi(c) = [] pi(c#) = [] pi(u) = [] pi(v) = [] pi(w) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: a#_A(x1) = x1 + 2 b_A(x1) = x1 + 15 b#_A(x1) = 7 a_A(x1) = x1 c_A(x1) = 0 c#_A(x1) = 7 u_A(x1) = x1 + 1 v_A(x1) = x1 + 1 w_A(x1) = 0 precedence: b# > c# > c = u = v = w > a > b > a# partial status: pi(a#) = [1] pi(b) = [1] pi(b#) = [] pi(a) = [] pi(c) = [] pi(c#) = [] pi(u) = [] pi(v) = [] pi(w) = [] The next rules are strictly ordered: p4, p8, p9 We remove them from the problem. -- SCC decomposition. 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: c#(a(x)) -> c#(x) p5: c#(a(x)) -> c#(c(x)) p6: c#(a(x)) -> a#(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 estimated dependency graph contains the following SCCs: {p4, p5} {p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: c#(a(x)) -> c#(c(x)) p2: 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 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: max/plus interpretations on natural numbers: c#_A(x1) = x1 + 2 a_A(x1) = x1 c_A(x1) = x1 b_A(x1) = max{0, x1 - 1} v_A(x1) = max{3, x1 + 2} u_A(x1) = x1 + 1 w_A(x1) = x1 + 1 precedence: c# = a = c = b = v = u = w partial status: pi(c#) = [] pi(a) = [] pi(c) = [] pi(b) = [] pi(v) = [] pi(u) = [] pi(w) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = max{0, x1 - 2} a_A(x1) = max{7, x1 + 3} c_A(x1) = x1 b_A(x1) = 9 v_A(x1) = 0 u_A(x1) = x1 + 1 w_A(x1) = x1 + 1 precedence: b > c = w > a > v > c# = u 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. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: 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} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: 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 set of usable rules consists of (no rules) Take the monotone reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = max{2, x1 + 1} a_A(x1) = max{1, x1} precedence: c# = a partial status: pi(c#) = [1] pi(a) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = x1 + 2 a_A(x1) = x1 + 1 precedence: c# = a partial status: pi(c#) = [1] pi(a) = [1] 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: 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: max/plus interpretations on natural numbers: b#_A(x1) = x1 c_A(x1) = x1 b_A(x1) = x1 a_A(x1) = max{0, x1 - 1} u_A(x1) = max{3, x1 + 2} w_A(x1) = x1 + 1 v_A(x1) = x1 + 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: max/plus interpretations on natural numbers: b#_A(x1) = max{4, x1 + 2} c_A(x1) = max{4, x1 + 3} b_A(x1) = x1 a_A(x1) = 0 u_A(x1) = 0 w_A(x1) = max{0, x1 - 2} v_A(x1) = x1 precedence: u > a = w = v > b > c > b# 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: max/plus interpretations on natural numbers: b#_A(x1) = max{4, x1 + 3} c_A(x1) = max{3, x1 + 2} precedence: b# = c partial status: pi(b#) = [1] pi(c) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: b#_A(x1) = max{1, x1 - 1} c_A(x1) = x1 precedence: b# = c partial status: pi(b#) = [] pi(c) = [1] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.