YES We show the termination of the TRS R: c(c(b(c(x)))) -> b(a(|0|(),c(x))) c(c(x)) -> b(c(b(c(x)))) a(|0|(),x) -> c(c(x)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(b(c(x)))) -> a#(|0|(),c(x)) p2: c#(c(x)) -> c#(b(c(x))) p3: a#(|0|(),x) -> c#(c(x)) p4: a#(|0|(),x) -> c#(x) and R consists of: r1: c(c(b(c(x)))) -> b(a(|0|(),c(x))) r2: c(c(x)) -> b(c(b(c(x)))) r3: a(|0|(),x) -> c(c(x)) The estimated dependency graph contains the following SCCs: {p1, p3, p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(b(c(x)))) -> a#(|0|(),c(x)) p2: a#(|0|(),x) -> c#(x) p3: a#(|0|(),x) -> c#(c(x)) and R consists of: r1: c(c(b(c(x)))) -> b(a(|0|(),c(x))) r2: c(c(x)) -> b(c(b(c(x)))) r3: a(|0|(),x) -> c(c(x)) The set of usable rules consists of r1, r2, r3 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 + (1,1) c_A(x1) = ((1,0),(0,0)) x1 + (1,0) b_A(x1) = ((1,0),(0,0)) x1 a#_A(x1,x2) = x1 + ((1,0),(0,0)) x2 + (0,1) |0|_A() = (2,0) a_A(x1,x2) = ((1,0),(1,0)) x2 + (2,1) precedence: c# = c = b = a# = |0| = a partial status: pi(c#) = [] pi(c) = [] pi(b) = [] pi(a#) = [] pi(|0|) = [] pi(a) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: c#_A(x1) = ((1,0),(1,0)) x1 c_A(x1) = (2,3) b_A(x1) = (1,1) a#_A(x1,x2) = (2,2) |0|_A() = (3,4) a_A(x1,x2) = (3,4) precedence: a > c# = c = a# = |0| > b partial status: pi(c#) = [] pi(c) = [] pi(b) = [] pi(a#) = [] pi(|0|) = [] pi(a) = [] 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(b(c(x)))) -> a#(|0|(),c(x)) p2: a#(|0|(),x) -> c#(c(x)) and R consists of: r1: c(c(b(c(x)))) -> b(a(|0|(),c(x))) r2: c(c(x)) -> b(c(b(c(x)))) r3: a(|0|(),x) -> c(c(x)) 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(b(c(x)))) -> a#(|0|(),c(x)) p2: a#(|0|(),x) -> c#(c(x)) and R consists of: r1: c(c(b(c(x)))) -> b(a(|0|(),c(x))) r2: c(c(x)) -> b(c(b(c(x)))) r3: a(|0|(),x) -> c(c(x)) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: c#_A(x1) = ((1,0),(0,0)) x1 + (1,6) c_A(x1) = ((0,1),(1,0)) x1 + (7,2) b_A(x1) = ((0,0),(0,1)) x1 + (4,3) a#_A(x1,x2) = x1 + ((0,1),(0,0)) x2 + (5,5) |0|_A() = (4,1) a_A(x1,x2) = x2 + (9,9) precedence: a > c > b > a# > c# = |0| partial status: pi(c#) = [] pi(c) = [] pi(b) = [] pi(a#) = [1] pi(|0|) = [] pi(a) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: c#_A(x1) = (0,0) c_A(x1) = (1,0) b_A(x1) = (0,0) a#_A(x1,x2) = ((0,1),(0,0)) x1 + (1,1) |0|_A() = (2,1) a_A(x1,x2) = (2,1) precedence: a > |0| > c > b > c# = a# partial status: pi(c#) = [] pi(c) = [] pi(b) = [] pi(a#) = [] pi(|0|) = [] pi(a) = [] 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: a#(|0|(),x) -> c#(c(x)) and R consists of: r1: c(c(b(c(x)))) -> b(a(|0|(),c(x))) r2: c(c(x)) -> b(c(b(c(x)))) r3: a(|0|(),x) -> c(c(x)) The estimated dependency graph contains the following SCCs: (no SCCs)