YES We show the termination of the TRS R: not(true()) -> false() not(false()) -> true() evenodd(x,|0|()) -> not(evenodd(x,s(|0|()))) evenodd(|0|(),s(|0|())) -> false() evenodd(s(x),s(|0|())) -> evenodd(x,|0|()) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: evenodd#(x,|0|()) -> not#(evenodd(x,s(|0|()))) p2: evenodd#(x,|0|()) -> evenodd#(x,s(|0|())) p3: evenodd#(s(x),s(|0|())) -> evenodd#(x,|0|()) and R consists of: r1: not(true()) -> false() r2: not(false()) -> true() r3: evenodd(x,|0|()) -> not(evenodd(x,s(|0|()))) r4: evenodd(|0|(),s(|0|())) -> false() r5: evenodd(s(x),s(|0|())) -> evenodd(x,|0|()) The estimated dependency graph contains the following SCCs: {p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: evenodd#(x,|0|()) -> evenodd#(x,s(|0|())) p2: evenodd#(s(x),s(|0|())) -> evenodd#(x,|0|()) and R consists of: r1: not(true()) -> false() r2: not(false()) -> true() r3: evenodd(x,|0|()) -> not(evenodd(x,s(|0|()))) r4: evenodd(|0|(),s(|0|())) -> false() r5: evenodd(s(x),s(|0|())) -> evenodd(x,|0|()) The set of usable rules consists of r1, r2 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: max/plus interpretation on natural numbers: evenodd#_A(x1,x2) = max{0, x2 - 11} |0|_A = 2 s_A(x1) = max{3, x1 - 10} not_A(x1) = max{3, x1 - 5} true_A = 0 false_A = 1 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: evenodd#_A(x1,x2) = max{0, x1 - 20, x2 - 16} |0|_A = 12 s_A(x1) = max{15, x1 + 3} not_A(x1) = max{1, x1 - 2} true_A = 0 false_A = 1 evenodd#!_A(x1,x2) = max{x1 + 3, x2 - 13} |0|!_A = 4 s!_A(x1) = max{5, x1 - 5} not!_A(x1) = max{2, x1 - 2} true!_A = 0 false!_A = 1 partial status: pi(evenodd#) = [] pi(|0|) = [] pi(s) = [] pi(not) = [] pi(true) = [] pi(false) = [] The following rules are removed: p2 -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: evenodd#(x,|0|()) -> evenodd#(x,s(|0|())) and R consists of: r1: not(true()) -> false() r2: not(false()) -> true() r3: evenodd(x,|0|()) -> not(evenodd(x,s(|0|()))) r4: evenodd(|0|(),s(|0|())) -> false() r5: evenodd(s(x),s(|0|())) -> evenodd(x,|0|()) The estimated dependency graph contains the following SCCs: (no SCCs)