YES We show the termination of the TRS R: times(x,|0|()) -> |0|() times(x,s(y)) -> plus(times(x,y),x) plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) plus(zero(),y) -> y plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) id(x) -> x if(true(),x,y) -> x if(false(),x,y) -> y not(x) -> if(x,false(),true()) gt(s(x),zero()) -> true() gt(zero(),y) -> false() gt(s(x),s(y)) -> gt(x,y) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: times#(x,s(y)) -> plus#(times(x,y),x) p2: times#(x,s(y)) -> times#(x,y) p3: plus#(s(x),s(y)) -> plus#(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))) p4: plus#(s(x),s(y)) -> if#(gt(x,y),x,y) p5: plus#(s(x),s(y)) -> gt#(x,y) p6: plus#(s(x),s(y)) -> if#(not(gt(x,y)),id(x),id(y)) p7: plus#(s(x),s(y)) -> not#(gt(x,y)) p8: plus#(s(x),s(y)) -> id#(x) p9: plus#(s(x),s(y)) -> id#(y) p10: plus#(s(x),x) -> plus#(if(gt(x,x),id(x),id(x)),s(x)) p11: plus#(s(x),x) -> if#(gt(x,x),id(x),id(x)) p12: plus#(s(x),x) -> gt#(x,x) p13: plus#(s(x),x) -> id#(x) p14: plus#(id(x),s(y)) -> plus#(x,if(gt(s(y),y),y,s(y))) p15: plus#(id(x),s(y)) -> if#(gt(s(y),y),y,s(y)) p16: plus#(id(x),s(y)) -> gt#(s(y),y) p17: not#(x) -> if#(x,false(),true()) p18: gt#(s(x),s(y)) -> gt#(x,y) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The estimated dependency graph contains the following SCCs: {p2} {p3, p10, p14} {p18} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: times#(x,s(y)) -> times#(x,y) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The set of usable rules consists of (no rules) Take the reduction pair: max/plus interpretations on natural numbers: times#_A(x1,x2) = x2 s_A(x1) = x1 + 1 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: plus#(s(x),s(y)) -> plus#(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))) p2: plus#(id(x),s(y)) -> plus#(x,if(gt(s(y),y),y,s(y))) p3: plus#(s(x),x) -> plus#(if(gt(x,x),id(x),id(x)),s(x)) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The set of usable rules consists of r7, r8, r9, r10, r11, r12, r13 Take the reduction pair: max/plus interpretations on natural numbers: plus#_A(x1,x2) = max{x1 + 6, x2 + 6} s_A(x1) = x1 + 1 if_A(x1,x2,x3) = max{x2, x3} gt_A(x1,x2) = max{x1, x2 + 1} not_A(x1) = max{2, x1 - 3} id_A(x1) = x1 true_A = 1 false_A = 1 zero_A = 1 The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: plus#(id(x),s(y)) -> plus#(x,if(gt(s(y),y),y,s(y))) p2: plus#(s(x),x) -> plus#(if(gt(x,x),id(x),id(x)),s(x)) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: plus#(id(x),s(y)) -> plus#(x,if(gt(s(y),y),y,s(y))) p2: plus#(s(x),x) -> plus#(if(gt(x,x),id(x),id(x)),s(x)) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The set of usable rules consists of r7, r8, r9, r11, r12, r13 Take the reduction pair: max/plus interpretations on natural numbers: plus#_A(x1,x2) = max{x1 + 11, x2 + 7} id_A(x1) = max{3, x1} s_A(x1) = x1 + 4 if_A(x1,x2,x3) = max{3, x1 - 6, x2, x3} gt_A(x1,x2) = max{x1 - 2, x2 + 1} true_A = 2 false_A = 1 zero_A = 1 The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: plus#(id(x),s(y)) -> plus#(x,if(gt(s(y),y),y,s(y))) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: plus#(id(x),s(y)) -> plus#(x,if(gt(s(y),y),y,s(y))) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The set of usable rules consists of r8, r9, r11, r12, r13 Take the reduction pair: max/plus interpretations on natural numbers: plus#_A(x1,x2) = max{2, x1} id_A(x1) = x1 + 5 s_A(x1) = x1 + 6 if_A(x1,x2,x3) = max{x1, x2, x3 + 1} gt_A(x1,x2) = max{x1 - 4, x2 + 5} zero_A = 7 false_A = 3 true_A = 0 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: gt#(s(x),s(y)) -> gt#(x,y) and R consists of: r1: times(x,|0|()) -> |0|() r2: times(x,s(y)) -> plus(times(x,y),x) r3: plus(s(x),s(y)) -> s(s(plus(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y))))) r4: plus(s(x),x) -> plus(if(gt(x,x),id(x),id(x)),s(x)) r5: plus(zero(),y) -> y r6: plus(id(x),s(y)) -> s(plus(x,if(gt(s(y),y),y,s(y)))) r7: id(x) -> x r8: if(true(),x,y) -> x r9: if(false(),x,y) -> y r10: not(x) -> if(x,false(),true()) r11: gt(s(x),zero()) -> true() r12: gt(zero(),y) -> false() r13: gt(s(x),s(y)) -> gt(x,y) The set of usable rules consists of (no rules) Take the reduction pair: max/plus interpretations on natural numbers: gt#_A(x1,x2) = max{x1 + 1, x2 + 1} s_A(x1) = x1 + 1 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.