YES We show the termination of the TRS R: h(x,c(y,z)) -> h(c(s(y),x),z) h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) p2: h#(c(s(x),c(s(|0|()),y)),z) -> h#(y,c(s(|0|()),c(x,z))) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) p2: h#(c(s(x),c(s(|0|()),y)),z) -> h#(y,c(s(|0|()),c(x,z))) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: h#_A(x1,x2) = x1 + ((0,0),(1,0)) x2 + (2,3) c_A(x1,x2) = x1 + x2 s_A(x1) = ((0,0),(1,0)) x1 |0|_A() = (1,2) precedence: h# = s = |0| > c partial status: pi(h#) = [] pi(c) = [2] pi(s) = [] pi(|0|) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: h#_A(x1,x2) = ((1,0),(1,0)) x2 + (3,0) c_A(x1,x2) = ((1,0),(0,0)) x2 + (2,3) s_A(x1) = (3,1) precedence: h# = c > s partial status: pi(h#) = [] pi(c) = [] pi(s) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.