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, r3, r4, r5 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: model-based reduction triple (=A, >=A!, >A!): finite algebra: carrier: {0,1} interpretations: evenodd#_A(0,0) = 0 evenodd#_A(0,1) = 0 evenodd#_A(1,0) = 0 evenodd#_A(1,1) = 0 |0|_A = 1 s_A(0) = 1 s_A(1) = 0 not_A(0) = 1 not_A(1) = 0 true_A = 0 false_A = 1 evenodd_A(0,0) = 0 evenodd_A(0,1) = 1 evenodd_A(1,0) = 1 evenodd_A(1,1) = 0 evenodd#!_A(0,0) = 1 evenodd#!_A(0,1) = 1 evenodd#!_A(1,0) = 1 evenodd#!_A(1,1) = 1 |0|!_A = 1 s!_A(0) = 1 s!_A(1) = 1 not!_A(0) = 0 not!_A(1) = 0 true!_A = 0 false!_A = 0 evenodd!_A(0,0) = 0 evenodd!_A(0,1) = 0 evenodd!_A(1,0) = 0 evenodd!_A(1,1) = 0 partial status: pi(evenodd#) = [1] pi(|0|) = [] pi(s) = [1] pi(not) = [] pi(true) = [] pi(false) = [] pi(evenodd) = [] 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)