MathDB
{x_i-a}+{x_{i+1}-b} at most 1/2024

Source: Malaysian SST 2023 P5

August 27, 2023
algebra

Problem Statement

Find the maximal value of c>0c>0 such that for any n1n\ge 1, and for any nn real numbers x1,,xnx_1, \cdots, x_n there exists real numbers a,ba ,b such that {xia}+{xi+1b}12024\{x_i-a\}+\{x_{i+1}-b\}\le \frac{1}{2024} for at least cncn indices ii. Here, xn+1=x1x_{n+1}=x_1 and {x}\{x\} denotes the fractional part of xx.
Proposed by Wong Jer Ren