Published online by Cambridge University Press: 30 May 2025
We define three new take-away games, the Rat game, the Mouse game and the Fat Rat game. Three winning strategies are given for the Rat game and outlined for the Mouse and Fat Rat games. The efficiencies of the strategies are determined. Whereas the winning strategies of nontrivial take-away games are based on irrational numbers, our games are based on rational numbers. Another motivation stems from a problem in combinatorial number theory.
The Rat game is played on 3 piles of tokens by 2 players who play alternately. Positions in the game are denoted throughout in the form (x, y, z), with 0 ≤ x ≤ y ≤ z, and moves in the form (x, y, z)→ (u, v, w), where of course also 0 ≤ u ≤ v ≤ w (see below). The player first unable to move—because the position is (0, 0, 0)—loses; the opponent wins.
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