Cumulative Subtraction Games
We study a variation of Nim-type subtraction games, called Cumulative Subtraction (CS). Two players alternate in removing pebbles out of a joint pile, and their actions add or remove points to a common score. We prove that the zero-sum outcome in optimal play of a CS with a finite number of possible actions is eventually periodic, with period $2s$, where $s$ is the size of the largest available action. This settles a conjecture by Stewart in his Ph.D. thesis (2011). Specifically, we find a quadratic bound, in the size of $s$, on when the outcome function must have become periodic. In case of exactly two possible actions, we give an explicit description of optimal play.
2019 ◽
Vol 12
(04)
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pp. 1950060
1974 ◽
Vol 32
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pp. 330-331
2016 ◽
Vol 3
(4)
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pp. 387-389
2019 ◽
Vol 139
(4)
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pp. 402-408
2014 ◽
Vol E97.A
(1)
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pp. 303-305
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