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 (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: evenodd#_A(x1,x2) = max{0, x1 - 18, x2 - 11} |0|_A = 2 s_A(x1) = x1 + 8 evenodd#!_A(x1,x2) = max{5, x1 - 16, x2 - 11} |0|!_A = 3 s!_A(x1) = max{4, x1 - 16} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: evenodd#_A(x1,x2) = max{0, x1 - 12, x2 - 7} |0|_A = 2 s_A(x1) = max{6, x1 + 4} evenodd#!_A(x1,x2) = max{3, x1 - 16, x2 - 16} |0|!_A = 1 s!_A(x1) = max{2, x1 - 15} partial status: pi(evenodd#) = [1] pi(|0|) = [] pi(s) = [1] 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)