MathDB
Winning Strategy? - [Canadian Repêchage 2011]

Source:

January 15, 2011
combinatorics proposedcombinatorics

Problem Statement

Alphonse and Beryl play a game starting with a blank blackboard. Alphonse goes first and the two players alternate turns. On Alphonse's first turn, he writes the integer 10201110^{2011} on the blackboard. On each subsequent turn, each player can do exactly one of the following two things:
(i) replace any number xx that is currently on the blackboard with two integers a and b greater than 11 such that x=ab,x = ab, or
(ii) erase one or two copies of a number yy that appears at least twice on the blackboard.
Thus, there may be many numbers on the board at any time. The first player who cannot do either of these things loses. Determine which player has a winning strategy and explain the strategy.