Sponsored by the Rutgers University Department of Mathematics and the
Center for Discrete Mathematics and Theoretical Computer Science (DIMACS)
Title: Subtraction-Division games, patterns, and self-similarity
Speaker: Elizabeth Kupin, Rutgers University
Date: Thursday, September 22, 2011 5:00pm
Location: Hill Center, Room 705, Rutgers University, Busch Campus, Piscataway, NJ
This talk will investigate a two player combinatorial game with parameters a, b and n. The game starts at a prearranged number n, and is a race to say the number 1. Each player, on his or her turn, can either subtract a from the current number, or divide the current number by b and round up. We will look at the Sprague-Grundy function of this game, and in particular, the sequence created by fixing a and b and letting n vary. While this sequence is not periodic, for many pairs of values a and b there are interesting patterns that appear. For certain pairs a and b, we will also be able to answer the more practical question - is there a simple formula for who wins?