MathDB
TOT 029 1982 Autumn S3 60 symbols, either X or O on paper

Source:

August 18, 2019
combinatoricsWordsgame strategygame

Problem Statement

6060 symbols, each of which is either XX or OO, are written consecutively on a strip of paper. This strip must then be cut into pieces with each piece containing symbols symmetric about their centre, e.g. O,XX,OXXXXX,XOXO, XX, OXXXXX, XOX, etc. (a) Prove that there is a way of cutting the strip so that there are no more than 2424 such pieces. (b) Give an example of such an arrangement of the signs for which the number of pieces cannot be less than 1515. (c) Try to improve the result of (b).