QUESTION

Alice and Bob play the following game. There is one pile of $N$ stones. Alice and Bob take turns to pick stones from the pile. Alice always begins by picking at least one, but less than $N$ stones. Thereafter, in each turn a player must pick at least one stone, but no more stones than were picked in the immediately preceding turn. The player who takes the last stone wins. With what property of $N$, will Alice win? When will Bob win?

For odd $N$ the outcome is quite clear, as Alice will start by picking one stone and will enforce the win. But what then?

Public Answer

VMHSVT The First Answerer