YES We show the termination of the TRS R: f(c(a(),z,x)) -> b(a(),z) b(x,b(z,y)) -> f(b(f(f(z)),c(x,z,y))) b(y,z) -> z -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(c(a(),z,x)) -> b#(a(),z) p2: b#(x,b(z,y)) -> f#(b(f(f(z)),c(x,z,y))) p3: b#(x,b(z,y)) -> b#(f(f(z)),c(x,z,y)) p4: b#(x,b(z,y)) -> f#(f(z)) p5: b#(x,b(z,y)) -> f#(z) and R consists of: r1: f(c(a(),z,x)) -> b(a(),z) r2: b(x,b(z,y)) -> f(b(f(f(z)),c(x,z,y))) r3: b(y,z) -> z The estimated dependency graph contains the following SCCs: {p1, p2, p4, p5} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(c(a(),z,x)) -> b#(a(),z) p2: b#(x,b(z,y)) -> f#(z) p3: b#(x,b(z,y)) -> f#(f(z)) p4: b#(x,b(z,y)) -> f#(b(f(f(z)),c(x,z,y))) and R consists of: r1: f(c(a(),z,x)) -> b(a(),z) r2: b(x,b(z,y)) -> f(b(f(f(z)),c(x,z,y))) r3: b(y,z) -> z 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: f#_A(x1) = ((0,1),(0,0)) x1 + (5,0) c_A(x1,x2,x3) = ((0,0),(1,1)) x2 + ((0,0),(0,1)) x3 + (5,0) a_A() = (1,1) b#_A(x1,x2) = ((1,1),(0,0)) x2 + (4,0) b_A(x1,x2) = ((1,1),(0,0)) x1 + ((1,1),(1,1)) x2 + (13,2) f_A(x1) = ((0,1),(0,1)) x1 + (16,2) precedence: f > c > a > f# = b# = b partial status: pi(f#) = [] pi(c) = [] pi(a) = [] pi(b#) = [] pi(b) = [2] pi(f) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1) = (2,1) c_A(x1,x2,x3) = (4,3) a_A() = (3,1) b#_A(x1,x2) = (2,1) b_A(x1,x2) = (1,2) f_A(x1) = (1,2) precedence: a > b = f > f# = b# > c partial status: pi(f#) = [] pi(c) = [] pi(a) = [] pi(b#) = [] pi(b) = [] pi(f) = [] The next rules are strictly ordered: p4 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(c(a(),z,x)) -> b#(a(),z) p2: b#(x,b(z,y)) -> f#(z) p3: b#(x,b(z,y)) -> f#(f(z)) and R consists of: r1: f(c(a(),z,x)) -> b(a(),z) r2: b(x,b(z,y)) -> f(b(f(f(z)),c(x,z,y))) r3: b(y,z) -> z 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: f#(c(a(),z,x)) -> b#(a(),z) p2: b#(x,b(z,y)) -> f#(f(z)) p3: b#(x,b(z,y)) -> f#(z) and R consists of: r1: f(c(a(),z,x)) -> b(a(),z) r2: b(x,b(z,y)) -> f(b(f(f(z)),c(x,z,y))) r3: b(y,z) -> z 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: f#_A(x1) = ((1,0),(0,0)) x1 + (3,10) c_A(x1,x2,x3) = ((1,1),(0,0)) x2 + ((1,1),(1,1)) x3 + (0,1) a_A() = (1,4) b#_A(x1,x2) = ((0,1),(0,0)) x2 + (2,10) b_A(x1,x2) = ((0,0),(1,1)) x1 + ((1,1),(1,1)) x2 + (2,9) f_A(x1) = ((1,0),(1,0)) x1 + (7,14) precedence: f# = c = b# = f > a = b partial status: pi(f#) = [] pi(c) = [] pi(a) = [] pi(b#) = [] pi(b) = [2] pi(f) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1) = (5,3) c_A(x1,x2,x3) = (3,0) a_A() = (1,1) b#_A(x1,x2) = (4,2) b_A(x1,x2) = x2 + (3,0) f_A(x1) = (5,0) precedence: a > c = b = f > f# > b# partial status: pi(f#) = [] pi(c) = [] pi(a) = [] pi(b#) = [] pi(b) = [2] pi(f) = [] The next rules are strictly ordered: p1, p2, p3 We remove them from the problem. Then no dependency pair remains.