25 men around a table
Source: Canadian Mathematical Olympiad - 1994 - Problem 3.
May 13, 2011
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Problem Statement
men sit around a circular table. Every hour there is a vote, and each must respond yes or no. Each man behaves as follows: on the , vote if his response is the same as the response of at least one of the two people he sits between, then he will respond the same way on the vote as on the vote; but if his response is different from that of both his neighbours on the vote, then his response on the vote will be different from his response on the vote. Prove that, however everybody responded on the first vote, there will be a time after which nobody's response will ever change.