YES We show the termination of the TRS R: f(|0|()) -> cons(|0|()) f(s(|0|())) -> f(p(s(|0|()))) p(s(X)) -> X -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(s(|0|())) -> f#(p(s(|0|()))) p2: f#(s(|0|())) -> p#(s(|0|())) and R consists of: r1: f(|0|()) -> cons(|0|()) r2: f(s(|0|())) -> f(p(s(|0|()))) r3: p(s(X)) -> X The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(s(|0|())) -> f#(p(s(|0|()))) and R consists of: r1: f(|0|()) -> cons(|0|()) r2: f(s(|0|())) -> f(p(s(|0|()))) r3: p(s(X)) -> X The set of usable rules consists of r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: f#_A(x1) = max{5, x1 + 3} s_A(x1) = max{12, x1 + 10} |0|_A = 0 p_A(x1) = max{6, x1 - 9} precedence: f# = s = |0| = p partial status: pi(f#) = [1] pi(s) = [1] pi(|0|) = [] pi(p) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: f#_A(x1) = max{11, x1 + 3} s_A(x1) = max{8, x1 + 5} |0|_A = 1 p_A(x1) = 0 precedence: f# = s = |0| = p partial status: pi(f#) = [1] pi(s) = [1] pi(|0|) = [] pi(p) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.