YES We show the termination of the TRS R: b(a(),b(c(z,x,y),a())) -> b(b(z,c(y,z,a())),x) f(c(a(),b(b(z,a()),y),x)) -> f(c(x,b(z,x),y)) c(f(c(a(),y,a())),x,z) -> f(b(b(z,z),f(b(y,b(x,a()))))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: b#(a(),b(c(z,x,y),a())) -> b#(b(z,c(y,z,a())),x) p2: b#(a(),b(c(z,x,y),a())) -> b#(z,c(y,z,a())) p3: b#(a(),b(c(z,x,y),a())) -> c#(y,z,a()) p4: f#(c(a(),b(b(z,a()),y),x)) -> f#(c(x,b(z,x),y)) p5: f#(c(a(),b(b(z,a()),y),x)) -> c#(x,b(z,x),y) p6: f#(c(a(),b(b(z,a()),y),x)) -> b#(z,x) p7: c#(f(c(a(),y,a())),x,z) -> f#(b(b(z,z),f(b(y,b(x,a()))))) p8: c#(f(c(a(),y,a())),x,z) -> b#(b(z,z),f(b(y,b(x,a())))) p9: c#(f(c(a(),y,a())),x,z) -> b#(z,z) p10: c#(f(c(a(),y,a())),x,z) -> f#(b(y,b(x,a()))) p11: c#(f(c(a(),y,a())),x,z) -> b#(y,b(x,a())) p12: c#(f(c(a(),y,a())),x,z) -> b#(x,a()) and R consists of: r1: b(a(),b(c(z,x,y),a())) -> b(b(z,c(y,z,a())),x) r2: f(c(a(),b(b(z,a()),y),x)) -> f(c(x,b(z,x),y)) r3: c(f(c(a(),y,a())),x,z) -> f(b(b(z,z),f(b(y,b(x,a()))))) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p11} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(a(),b(c(z,x,y),a())) -> b#(b(z,c(y,z,a())),x) p2: b#(a(),b(c(z,x,y),a())) -> c#(y,z,a()) p3: c#(f(c(a(),y,a())),x,z) -> b#(y,b(x,a())) p4: b#(a(),b(c(z,x,y),a())) -> b#(z,c(y,z,a())) p5: c#(f(c(a(),y,a())),x,z) -> f#(b(y,b(x,a()))) p6: f#(c(a(),b(b(z,a()),y),x)) -> b#(z,x) p7: f#(c(a(),b(b(z,a()),y),x)) -> c#(x,b(z,x),y) p8: c#(f(c(a(),y,a())),x,z) -> b#(z,z) p9: c#(f(c(a(),y,a())),x,z) -> b#(b(z,z),f(b(y,b(x,a())))) p10: c#(f(c(a(),y,a())),x,z) -> f#(b(b(z,z),f(b(y,b(x,a()))))) p11: f#(c(a(),b(b(z,a()),y),x)) -> f#(c(x,b(z,x),y)) and R consists of: r1: b(a(),b(c(z,x,y),a())) -> b(b(z,c(y,z,a())),x) r2: f(c(a(),b(b(z,a()),y),x)) -> f(c(x,b(z,x),y)) r3: c(f(c(a(),y,a())),x,z) -> f(b(b(z,z),f(b(y,b(x,a()))))) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = (2,1) a_A() = (1,1) b_A(x1,x2) = ((1,1),(0,0)) x1 + x2 + (1,1) c_A(x1,x2,x3) = ((1,1),(0,0)) x1 + ((0,0),(1,1)) x2 + ((0,1),(1,0)) x3 + (1,1) c#_A(x1,x2,x3) = (2,1) f_A(x1) = x1 f#_A(x1) = ((0,1),(0,1)) x1 2. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = (0,0) a_A() = (1,1) b_A(x1,x2) = x1 + ((0,1),(0,0)) x2 + (1,0) c_A(x1,x2,x3) = (1,1) c#_A(x1,x2,x3) = (0,0) f_A(x1) = (2,0) f#_A(x1) = (1,1) 3. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = (1,0) a_A() = (1,1) b_A(x1,x2) = (0,1) c_A(x1,x2,x3) = (1,1) c#_A(x1,x2,x3) = (1,0) f_A(x1) = (2,2) f#_A(x1) = (0,1) The next rules are strictly ordered: p5, p6, p7, p10, p11 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: b#(a(),b(c(z,x,y),a())) -> b#(b(z,c(y,z,a())),x) p2: b#(a(),b(c(z,x,y),a())) -> c#(y,z,a()) p3: c#(f(c(a(),y,a())),x,z) -> b#(y,b(x,a())) p4: b#(a(),b(c(z,x,y),a())) -> b#(z,c(y,z,a())) p5: c#(f(c(a(),y,a())),x,z) -> b#(z,z) p6: c#(f(c(a(),y,a())),x,z) -> b#(b(z,z),f(b(y,b(x,a())))) and R consists of: r1: b(a(),b(c(z,x,y),a())) -> b(b(z,c(y,z,a())),x) r2: f(c(a(),b(b(z,a()),y),x)) -> f(c(x,b(z,x),y)) r3: c(f(c(a(),y,a())),x,z) -> f(b(b(z,z),f(b(y,b(x,a()))))) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5, p6} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(a(),b(c(z,x,y),a())) -> b#(b(z,c(y,z,a())),x) p2: b#(a(),b(c(z,x,y),a())) -> b#(z,c(y,z,a())) p3: b#(a(),b(c(z,x,y),a())) -> c#(y,z,a()) p4: c#(f(c(a(),y,a())),x,z) -> b#(b(z,z),f(b(y,b(x,a())))) p5: c#(f(c(a(),y,a())),x,z) -> b#(z,z) p6: c#(f(c(a(),y,a())),x,z) -> b#(y,b(x,a())) and R consists of: r1: b(a(),b(c(z,x,y),a())) -> b(b(z,c(y,z,a())),x) r2: f(c(a(),b(b(z,a()),y),x)) -> f(c(x,b(z,x),y)) r3: c(f(c(a(),y,a())),x,z) -> f(b(b(z,z),f(b(y,b(x,a()))))) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = x2 a_A() = (0,1) b_A(x1,x2) = ((1,1),(0,0)) x1 + x2 + (1,1) c_A(x1,x2,x3) = ((1,1),(0,0)) x1 + ((0,0),(1,0)) x2 + ((1,1),(1,0)) x3 + (1,2) c#_A(x1,x2,x3) = ((1,1),(0,0)) x2 + x3 + (2,0) f_A(x1) = ((0,1),(0,0)) x1 + (0,1) 2. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = x2 a_A() = (1,1) b_A(x1,x2) = (1,1) c_A(x1,x2,x3) = (0,1) c#_A(x1,x2,x3) = x3 + (2,1) f_A(x1) = (2,2) 3. matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = ((0,1),(0,0)) x2 + (1,1) a_A() = (1,1) b_A(x1,x2) = (1,1) c_A(x1,x2,x3) = (1,1) c#_A(x1,x2,x3) = (0,0) f_A(x1) = (2,0) The next rules are strictly ordered: p1, p2, p3, p4, p5, p6 We remove them from the problem. Then no dependency pair remains.