YES We show the termination of the TRS R: b(b(|0|(),y),x) -> y c(c(c(y))) -> c(c(a(a(c(b(|0|(),y)),|0|()),|0|()))) a(y,|0|()) -> b(y,|0|()) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: c#(c(c(y))) -> c#(c(a(a(c(b(|0|(),y)),|0|()),|0|()))) p2: c#(c(c(y))) -> c#(a(a(c(b(|0|(),y)),|0|()),|0|())) p3: c#(c(c(y))) -> a#(a(c(b(|0|(),y)),|0|()),|0|()) p4: c#(c(c(y))) -> a#(c(b(|0|(),y)),|0|()) p5: c#(c(c(y))) -> c#(b(|0|(),y)) p6: c#(c(c(y))) -> b#(|0|(),y) p7: a#(y,|0|()) -> b#(y,|0|()) and R consists of: r1: b(b(|0|(),y),x) -> y r2: c(c(c(y))) -> c(c(a(a(c(b(|0|(),y)),|0|()),|0|()))) r3: a(y,|0|()) -> b(y,|0|()) 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(c(y))) -> c#(c(a(a(c(b(|0|(),y)),|0|()),|0|()))) p2: c#(c(c(y))) -> c#(a(a(c(b(|0|(),y)),|0|()),|0|())) and R consists of: r1: b(b(|0|(),y),x) -> y r2: c(c(c(y))) -> c(c(a(a(c(b(|0|(),y)),|0|()),|0|()))) r3: a(y,|0|()) -> b(y,|0|()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. max/plus interpretations on natural numbers: c#_A(x1) = max{0, x1 - 39} c_A(x1) = x1 + 28 a_A(x1,x2) = max{x1 - 5, x2 + 10} b_A(x1,x2) = max{9, x1 - 6, x2 + 7} |0|_A = 0 2. max/plus interpretations on natural numbers: c#_A(x1) = 0 c_A(x1) = x1 + 2 a_A(x1,x2) = 3 b_A(x1,x2) = 4 |0|_A = 0 The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.