Shunsuke Nakamura, Ryo Hanafusa, Wataru Ogasa, Takeru Kitagawa and Ryohei Miyadera
We study chocolate games that are variants of a game of Nim. We can cut the chocolate games in 3 directions, and we represent the chocolates with coordinates 

, where 

 are the maximum times you can cut them in each direction. 
The coordinates 

 of the chocolates satisfy the inequalities 

 for 

.
For 

 we prove a theorem for the L-state (loser's state), and the proof of this theorem can be easily generalized to the case of an arbitrary even number 

.
For 

 we prove a theorem for the L-state (loser's state), and we need the theory of Grundy numbers to prove the theorem. The generalization of the case of 

 to the case of an arbitrary odd number is an open problem.
The authors present beautiful graphs made by Grundy numbers of these chocolate games.