YES We show the termination of the TRS R: cond1(true(),x,y) -> cond2(gr(y,|0|()),x,y) cond2(true(),x,y) -> cond2(gr(y,|0|()),x,p(y)) cond2(false(),x,y) -> cond1(gr(x,|0|()),p(x),y) gr(|0|(),x) -> false() gr(s(x),|0|()) -> true() gr(s(x),s(y)) -> gr(x,y) p(|0|()) -> |0|() p(s(x)) -> x -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: cond1#(true(),x,y) -> cond2#(gr(y,|0|()),x,y) p2: cond1#(true(),x,y) -> gr#(y,|0|()) p3: cond2#(true(),x,y) -> cond2#(gr(y,|0|()),x,p(y)) p4: cond2#(true(),x,y) -> gr#(y,|0|()) p5: cond2#(true(),x,y) -> p#(y) p6: cond2#(false(),x,y) -> cond1#(gr(x,|0|()),p(x),y) p7: cond2#(false(),x,y) -> gr#(x,|0|()) p8: cond2#(false(),x,y) -> p#(x) p9: gr#(s(x),s(y)) -> gr#(x,y) and R consists of: r1: cond1(true(),x,y) -> cond2(gr(y,|0|()),x,y) r2: cond2(true(),x,y) -> cond2(gr(y,|0|()),x,p(y)) r3: cond2(false(),x,y) -> cond1(gr(x,|0|()),p(x),y) r4: gr(|0|(),x) -> false() r5: gr(s(x),|0|()) -> true() r6: gr(s(x),s(y)) -> gr(x,y) r7: p(|0|()) -> |0|() r8: p(s(x)) -> x The estimated dependency graph contains the following SCCs: {p1, p3, p6} {p9} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: cond1#(true(),x,y) -> cond2#(gr(y,|0|()),x,y) p2: cond2#(false(),x,y) -> cond1#(gr(x,|0|()),p(x),y) p3: cond2#(true(),x,y) -> cond2#(gr(y,|0|()),x,p(y)) and R consists of: r1: cond1(true(),x,y) -> cond2(gr(y,|0|()),x,y) r2: cond2(true(),x,y) -> cond2(gr(y,|0|()),x,p(y)) r3: cond2(false(),x,y) -> cond1(gr(x,|0|()),p(x),y) r4: gr(|0|(),x) -> false() r5: gr(s(x),|0|()) -> true() r6: gr(s(x),s(y)) -> gr(x,y) r7: p(|0|()) -> |0|() r8: p(s(x)) -> x The set of usable rules consists of r4, r5, r7, r8 Take the reduction pair: generalized weighted path order (>=MG, >MG) base order 1: max/plus interpretation on natural numbers: cond1#_A(x1,x2,x3) = max{x1 + 7, x2 + 14} true_A = 16 cond2#_A(x1,x2,x3) = max{22, x2 + 14} gr_A(x1,x2) = max{12, x1 + 6} |0|_A = 7 false_A = 12 p_A(x1) = max{7, x1 - 6} s_A(x1) = max{13, x1 + 11} base order 2: precedence: cond1# > cond2# > true = false = s > gr = p > |0| partial status: pi(cond1#) = [] pi(true) = [] pi(cond2#) = [] pi(gr) = [] pi(|0|) = [] pi(false) = [] pi(p) = [] pi(s) = [] The following rules are removed: p2 -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: cond1#(true(),x,y) -> cond2#(gr(y,|0|()),x,y) p2: cond2#(true(),x,y) -> cond2#(gr(y,|0|()),x,p(y)) and R consists of: r1: cond1(true(),x,y) -> cond2(gr(y,|0|()),x,y) r2: cond2(true(),x,y) -> cond2(gr(y,|0|()),x,p(y)) r3: cond2(false(),x,y) -> cond1(gr(x,|0|()),p(x),y) r4: gr(|0|(),x) -> false() r5: gr(s(x),|0|()) -> true() r6: gr(s(x),s(y)) -> gr(x,y) r7: p(|0|()) -> |0|() r8: p(s(x)) -> x The estimated dependency graph contains the following SCCs: {p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: cond2#(true(),x,y) -> cond2#(gr(y,|0|()),x,p(y)) and R consists of: r1: cond1(true(),x,y) -> cond2(gr(y,|0|()),x,y) r2: cond2(true(),x,y) -> cond2(gr(y,|0|()),x,p(y)) r3: cond2(false(),x,y) -> cond1(gr(x,|0|()),p(x),y) r4: gr(|0|(),x) -> false() r5: gr(s(x),|0|()) -> true() r6: gr(s(x),s(y)) -> gr(x,y) r7: p(|0|()) -> |0|() r8: p(s(x)) -> x The set of usable rules consists of r4, r5, r6, r7, r8 Take the reduction pair: generalized weighted path order (>=MG, >MG) base order 1: max/plus interpretation on natural numbers: cond2#_A(x1,x2,x3) = max{x1 - 6, x3 + 11} true_A = 27 gr_A(x1,x2) = max{5, x1 + 2} |0|_A = 8 p_A(x1) = max{9, x1 - 12} false_A = 3 s_A(x1) = max{28, x1 + 26} base order 2: precedence: cond2# > |0| = s > true > gr > false > p partial status: pi(cond2#) = [] pi(true) = [] pi(gr) = [1] pi(|0|) = [] pi(p) = [] pi(false) = [] pi(s) = [1] The following rules are removed: p1 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: gr#(s(x),s(y)) -> gr#(x,y) and R consists of: r1: cond1(true(),x,y) -> cond2(gr(y,|0|()),x,y) r2: cond2(true(),x,y) -> cond2(gr(y,|0|()),x,p(y)) r3: cond2(false(),x,y) -> cond1(gr(x,|0|()),p(x),y) r4: gr(|0|(),x) -> false() r5: gr(s(x),|0|()) -> true() r6: gr(s(x),s(y)) -> gr(x,y) r7: p(|0|()) -> |0|() r8: p(s(x)) -> x The set of usable rules consists of r4, r5, r6, r8 Take the reduction pair: generalized weighted path order (>=MG, >MG) base order 1: max/plus interpretation on natural numbers: gr#_A(x1,x2) = max{x1 - 1, x2 + 16} s_A(x1) = max{21, x1 + 15} gr_A(x1,x2) = max{4, x1 - 22, x2 - 16} |0|_A = 11 false_A = 1 true_A = 3 p_A(x1) = max{13, x1 - 14} base order 2: precedence: p > |0| > gr# = gr = true > s = false partial status: pi(gr#) = [2] pi(s) = [1] pi(gr) = [] pi(|0|) = [] pi(false) = [] pi(true) = [] pi(p) = [] The following rules are removed: p1 Then no dependency pair remains.