Israel 2015 Q6 - Shifting lamps process
Source: Israel National Olympiad 2015 Q6
August 7, 2019
combinatoricsProcesseslamps
Problem Statement
Let be a positive integer. lamps are placed in a line. At minute 0, some lamps are on (maybe all of them). Every minute the state of the lamps changes: A lamp is on at minute if and only if at minute , exactly one of its neighbors is on (the two lamps at the ends have one neighbor each, all other lamps have two neighbors).For which values of can we guarantee that all lamps will be off after some time?