MathDB
I see equally many knights to my left and to my right, knights always tell truth

Source: 2019 RMM Shortlist C1

June 19, 2020
combinatorics

Problem Statement

Let kk and NN be integers such that k>1k > 1 and N>2k+1N > 2k + 1. A number of NN persons sit around the Round Table, equally spaced. Each person is either a knight (always telling the truth) or a liar (who always lies). Each person sees the nearest k persons clockwise, and the nearest kk persons anticlockwise. Each person says: ''I see equally many knights to my left and to my right." Establish, in terms of kk and NN, whether the persons around the Table are necessarily all knights.
Sergey Berlov, Russia