YES We show the termination of the TRS R: f(x,c(y)) -> f(x,s(f(y,y))) f(s(x),y) -> f(x,s(c(y))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,c(y)) -> f#(x,s(f(y,y))) p2: f#(x,c(y)) -> f#(y,y) p3: f#(s(x),y) -> f#(x,s(c(y))) and R consists of: r1: f(x,c(y)) -> f(x,s(f(y,y))) r2: f(s(x),y) -> f(x,s(c(y))) The estimated dependency graph contains the following SCCs: {p2} {p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,c(y)) -> f#(y,y) and R consists of: r1: f(x,c(y)) -> f(x,s(f(y,y))) r2: f(s(x),y) -> f(x,s(c(y))) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: f#_A(x1,x2) = x2 c_A(x1) = x1 + 2 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: f#_A(x1,x2) = max{x1, x2} c_A(x1) = max{4, x1} f#!_A(x1,x2) = max{1, x1 - 7, x2 - 7} c!_A(x1) = max{3, x1 - 6} partial status: pi(f#) = [2] pi(c) = [] The following rules are removed: p1 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(s(x),y) -> f#(x,s(c(y))) and R consists of: r1: f(x,c(y)) -> f(x,s(f(y,y))) r2: f(s(x),y) -> f(x,s(c(y))) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: f#_A(x1,x2) = x1 s_A(x1) = x1 + 2 c_A(x1) = 4 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: f#_A(x1,x2) = 0 s_A(x1) = 4 c_A(x1) = x1 + 5 f#!_A(x1,x2) = max{x1 - 1, x2 + 5} s!_A(x1) = 1 c!_A(x1) = 4 partial status: pi(f#) = [1] pi(s) = [] pi(c) = [] The following rules are removed: p1 Then no dependency pair remains.