YES We show the termination of the relative TRS R/S: R: minus(x,o()) -> x minus(s(x),s(y)) -> minus(x,y) div(|0|(),s(y)) -> |0|() div(s(x),s(y)) -> s(div(minus(x,y),s(y))) divL(x,nil()) -> x divL(x,cons(y,xs)) -> divL(div(x,y),xs) S: cons(x,cons(y,xs)) -> cons(y,cons(x,xs)) -- SCC decomposition. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: minus#(s(x),s(y)) -> minus#(x,y) p2: div#(s(x),s(y)) -> div#(minus(x,y),s(y)) p3: div#(s(x),s(y)) -> minus#(x,y) p4: divL#(x,cons(y,xs)) -> divL#(div(x,y),xs) p5: divL#(x,cons(y,xs)) -> div#(x,y) and R consists of: r1: minus(x,o()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: div(|0|(),s(y)) -> |0|() r4: div(s(x),s(y)) -> s(div(minus(x,y),s(y))) r5: divL(x,nil()) -> x r6: divL(x,cons(y,xs)) -> divL(div(x,y),xs) r7: cons(x,cons(y,xs)) -> cons(y,cons(x,xs)) The estimated dependency graph contains the following SCCs: {p4} {p2} {p1} -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: divL#(x,cons(y,xs)) -> divL#(div(x,y),xs) and R consists of: r1: minus(x,o()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: div(|0|(),s(y)) -> |0|() r4: div(s(x),s(y)) -> s(div(minus(x,y),s(y))) r5: divL(x,nil()) -> x r6: divL(x,cons(y,xs)) -> divL(div(x,y),xs) r7: cons(x,cons(y,xs)) -> cons(y,cons(x,xs)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7 Take the reduction pair: max/plus interpretations on natural numbers: divL#_A(x1,x2) = max{2, x2} cons_A(x1,x2) = x2 + 8 div_A(x1,x2) = max{1, x1} minus_A(x1,x2) = max{1, x1} o_A = 0 s_A(x1) = max{3, x1 + 2} |0|_A = 2 divL_A(x1,x2) = max{x1 + 7, x2} nil_A = 0 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: div#(s(x),s(y)) -> div#(minus(x,y),s(y)) and R consists of: r1: minus(x,o()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: div(|0|(),s(y)) -> |0|() r4: div(s(x),s(y)) -> s(div(minus(x,y),s(y))) r5: divL(x,nil()) -> x r6: divL(x,cons(y,xs)) -> divL(div(x,y),xs) r7: cons(x,cons(y,xs)) -> cons(y,cons(x,xs)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7 Take the reduction pair: max/plus interpretations on natural numbers: div#_A(x1,x2) = max{2, x1} s_A(x1) = max{4, x1 + 3} minus_A(x1,x2) = max{1, x1} o_A = 0 div_A(x1,x2) = x1 |0|_A = 1 divL_A(x1,x2) = max{x1 + 1, x2} nil_A = 0 cons_A(x1,x2) = x2 + 1 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: minus#(s(x),s(y)) -> minus#(x,y) and R consists of: r1: minus(x,o()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: div(|0|(),s(y)) -> |0|() r4: div(s(x),s(y)) -> s(div(minus(x,y),s(y))) r5: divL(x,nil()) -> x r6: divL(x,cons(y,xs)) -> divL(div(x,y),xs) r7: cons(x,cons(y,xs)) -> cons(y,cons(x,xs)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7 Take the reduction pair: max/plus interpretations on natural numbers: minus#_A(x1,x2) = max{x1, x2} s_A(x1) = max{2, x1 + 1} minus_A(x1,x2) = max{1, x1} o_A = 0 div_A(x1,x2) = x1 |0|_A = 1 divL_A(x1,x2) = max{x1 + 3, x2} nil_A = 0 cons_A(x1,x2) = x2 + 3 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.