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Inequality on 2v elements [Cyprus IMO TST 2018]

Source: Cyprus IMO TST 2018, Problem 4

July 1, 2018
inequalities

Problem Statement

Let Λ={1,2,,2v1,2v}\Lambda= \{1, 2, \ldots, 2v-1,2v\} and P={α1,α2,,α2v1,α2v}P=\{\alpha_1, \alpha_2, \ldots, \alpha_{2v-1}, \alpha_{2v}\} be a permutation of the elements of Λ\Lambda.
(a) Prove that i=1vα2i1α2ii=1v(2i1)2i.\sum_{i=1}^v \alpha_{2i-1}\alpha_{2i} \leq \sum_{i=1}^v (2i-1)2i. (b) Determine the largest positive integer mm such that we can partition the m×mm\times m square into 77 rectangles for which every pair of them has no common interior points and their lengths and widths form the following sequence: 1,2,3,4,5,6,7,8,9,10,11,12,13,14.1,2,3,4,5,6,7,8,9,10,11,12,13,14.