“…To this end, we therefore assume that (a) we did prolong an extreme edge of P 1 (it has to be the bottom one), or that (b) the step r has size b/(a + 1) + 1. We cut P * and P in the same way as in Case (2) and we define, for 1 ≤ i ≤ 3, the variables P i and P * i , as well as BL , S, S , s and s in the same way as in Case (2). Note that r is in S and in S .…”