Cumulative subtraction games
The electronic journal of combinatorics, Tome 26 (2019) no. 4
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.
DOI :
10.37236/7904
Classification :
91A46, 91A05
Mots-clés : combinatorial games, two players, zero-sum outcome, Nim-like game, subtraction game
Mots-clés : combinatorial games, two players, zero-sum outcome, Nim-like game, subtraction game
@article{10_37236_7904,
author = {Gal Cohensius and Urban Larsson and Reshef Meir and David Wahlstedt},
title = {Cumulative subtraction games},
journal = {The electronic journal of combinatorics},
year = {2019},
volume = {26},
number = {4},
doi = {10.37236/7904},
zbl = {1442.91015},
url = {http://geodesic.mathdoc.fr/articles/10.37236/7904/}
}
Gal Cohensius; Urban Larsson; Reshef Meir; David Wahlstedt. Cumulative subtraction games. The electronic journal of combinatorics, Tome 26 (2019) no. 4. doi: 10.37236/7904
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