YES We show the termination of the TRS R: nonZero(|0|()) -> false() nonZero(s(x)) -> true() p(|0|()) -> |0|() p(s(x)) -> x id_inc(x) -> x id_inc(x) -> s(x) random(x) -> rand(x,|0|()) rand(x,y) -> if(nonZero(x),x,y) if(false(),x,y) -> y if(true(),x,y) -> rand(p(x),id_inc(y)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: random#(x) -> rand#(x,|0|()) p2: rand#(x,y) -> if#(nonZero(x),x,y) p3: rand#(x,y) -> nonZero#(x) p4: if#(true(),x,y) -> rand#(p(x),id_inc(y)) p5: if#(true(),x,y) -> p#(x) p6: if#(true(),x,y) -> id_inc#(y) and R consists of: r1: nonZero(|0|()) -> false() r2: nonZero(s(x)) -> true() r3: p(|0|()) -> |0|() r4: p(s(x)) -> x r5: id_inc(x) -> x r6: id_inc(x) -> s(x) r7: random(x) -> rand(x,|0|()) r8: rand(x,y) -> if(nonZero(x),x,y) r9: if(false(),x,y) -> y r10: if(true(),x,y) -> rand(p(x),id_inc(y)) The estimated dependency graph contains the following SCCs: {p2, p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: rand#(x,y) -> if#(nonZero(x),x,y) p2: if#(true(),x,y) -> rand#(p(x),id_inc(y)) and R consists of: r1: nonZero(|0|()) -> false() r2: nonZero(s(x)) -> true() r3: p(|0|()) -> |0|() r4: p(s(x)) -> x r5: id_inc(x) -> x r6: id_inc(x) -> s(x) r7: random(x) -> rand(x,|0|()) r8: rand(x,y) -> if(nonZero(x),x,y) r9: if(false(),x,y) -> y r10: if(true(),x,y) -> rand(p(x),id_inc(y)) The set of usable rules consists of r1, r2, r3, r4, r5, r6 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: rand#_A(x1,x2) = 1 if#_A(x1,x2,x3) = 1 nonZero_A(x1) = max{4, x1 - 2} true_A = 13 p_A(x1) = max{5, x1 - 4} id_inc_A(x1) = x1 + 15 |0|_A = 5 false_A = 4 s_A(x1) = x1 + 15 rand#!_A(x1,x2) = x1 + 2 if#!_A(x1,x2,x3) = max{1, x1 - 5, x2 - 1} nonZero!_A(x1) = max{8, x1 + 1} true!_A = 3 p!_A(x1) = max{17, x1 - 6} id_inc!_A(x1) = max{9, x1 - 18} |0|!_A = 8 false!_A = 7 s!_A(x1) = max{4, x1 - 19} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: rand#_A(x1,x2) = max{1, x1 - 2} if#_A(x1,x2,x3) = max{1, x2 - 2} nonZero_A(x1) = max{0, x1 - 3} true_A = 2 p_A(x1) = max{1, x1} id_inc_A(x1) = max{8, x1 + 1} |0|_A = 2 false_A = 0 s_A(x1) = max{8, x1 + 1} rand#!_A(x1,x2) = max{9, x2 + 1} if#!_A(x1,x2,x3) = x3 + 10 nonZero!_A(x1) = max{0, x1 - 6} true!_A = 1 p!_A(x1) = max{13, x1 - 5} id_inc!_A(x1) = max{11, x1 - 1} |0|!_A = 2 false!_A = 1 s!_A(x1) = max{10, x1 - 2} partial status: pi(rand#) = [] pi(if#) = [] pi(nonZero) = [1] pi(true) = [] pi(p) = [1] pi(id_inc) = [1] pi(|0|) = [] pi(false) = [] pi(s) = [1] The following rules are removed: p1, p2 Then no dependency pair remains.