YES We show the termination of the TRS R: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) c(c(a(a(y,|0|()),x))) -> c(y) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(c(a(x,y)))) -> c#(c(c(c(y)))) p2: c#(c(c(a(x,y)))) -> c#(c(c(y))) p3: c#(c(c(a(x,y)))) -> c#(c(y)) p4: c#(c(c(a(x,y)))) -> c#(y) p5: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) p6: c#(c(b(c(y),|0|()))) -> c#(a(y,|0|())) p7: c#(c(a(a(y,|0|()),x))) -> c#(y) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5, p7} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(c(a(x,y)))) -> c#(c(c(c(y)))) p2: c#(c(a(a(y,|0|()),x))) -> c#(y) p3: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) p4: c#(c(c(a(x,y)))) -> c#(y) p5: c#(c(c(a(x,y)))) -> c#(c(y)) p6: c#(c(c(a(x,y)))) -> c#(c(c(y))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The set of usable rules consists of r1, r2, r3 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = x1 + 2 c_A(x1) = x1 + 21 a_A(x1,x2) = max{x1 - 9, x2 + 24} |0|_A = 22 b_A(x1,x2) = max{70, x1 + 3, x2 - 2} precedence: c = a = |0| = b > c# partial status: pi(c#) = [1] pi(c) = [] pi(a) = [] pi(|0|) = [] pi(b) = [] 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#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) p3: c#(c(c(a(x,y)))) -> c#(y) p4: c#(c(c(a(x,y)))) -> c#(c(y)) p5: c#(c(c(a(x,y)))) -> c#(c(c(y))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) 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: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(c(a(x,y)))) -> c#(c(c(y))) p3: c#(c(c(a(x,y)))) -> c#(c(y)) p4: c#(c(c(a(x,y)))) -> c#(y) p5: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The set of usable rules consists of r1, r2, r3 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = max{19, x1 - 96} c_A(x1) = max{78, x1 + 36} a_A(x1,x2) = max{71, x1 - 8, x2 + 30} |0|_A = 9 b_A(x1,x2) = max{x1 - 8, x2 + 98} precedence: c# = c = a = |0| = b partial status: pi(c#) = [] pi(c) = [] pi(a) = [2] pi(|0|) = [] pi(b) = [2] The next rules are strictly ordered: p3 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(c(a(x,y)))) -> c#(c(c(y))) p3: c#(c(c(a(x,y)))) -> c#(y) p4: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) p3: c#(c(c(a(x,y)))) -> c#(y) p4: c#(c(c(a(x,y)))) -> c#(c(c(y))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The set of usable rules consists of r1, r2, r3 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = max{13, x1 + 6} c_A(x1) = max{62, x1 + 45} a_A(x1,x2) = max{x1 - 19, x2 + 15} |0|_A = 0 b_A(x1,x2) = max{151, x1 - 48, x2 + 1} precedence: a = b > c# > c = |0| partial status: pi(c#) = [1] pi(c) = [] pi(a) = [] pi(|0|) = [] pi(b) = [2] The next rules are strictly ordered: p3 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) p3: c#(c(c(a(x,y)))) -> c#(c(c(y))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The estimated dependency graph contains the following SCCs: {p1, p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(c(a(x,y)))) -> c#(c(c(y))) p3: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The set of usable rules consists of r1, r2, r3 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = max{1, x1 - 79} c_A(x1) = max{31, x1 + 22} a_A(x1,x2) = max{64, x1 - 1, x2 + 55} |0|_A = 5 b_A(x1,x2) = max{120, x1 + 32, x2 + 54} precedence: c# = c = a = |0| = b partial status: pi(c#) = [] pi(c) = [] pi(a) = [] pi(|0|) = [] pi(b) = [] 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: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(a(a(y,|0|()),x))) -> c#(y) p2: c#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: c#_A(x1) = max{33, x1 + 17} c_A(x1) = x1 + 7 a_A(x1,x2) = max{x1 + 8, x2 - 2} |0|_A = 12 b_A(x1,x2) = max{11, x1 + 7, x2} precedence: c# = c = a = |0| = b partial status: pi(c#) = [] pi(c) = [1] pi(a) = [1] pi(|0|) = [] pi(b) = [2] 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#(c(b(c(y),|0|()))) -> c#(c(a(y,|0|()))) and R consists of: r1: c(c(c(a(x,y)))) -> b(c(c(c(c(y)))),x) r2: c(c(b(c(y),|0|()))) -> a(|0|(),c(c(a(y,|0|())))) r3: c(c(a(a(y,|0|()),x))) -> c(y) The estimated dependency graph contains the following SCCs: (no SCCs)