Tie-breaking in self interest cumulative subtraction games

Fuente: arXiv
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Autori principali: Bhagat, Anjali, Kulkarni, Tanmay, Larsson, Urban, Murali, Divya
Natura: Preprint
Pubblicazione: 2025
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author Bhagat, Anjali
Kulkarni, Tanmay
Larsson, Urban
Murali, Divya
author_facet Bhagat, Anjali
Kulkarni, Tanmay
Larsson, Urban
Murali, Divya
contents Subtraction games have a rich literature as normal-play combinatorial games (e.g., Berlekamp, Conway, and Guy, 1982). Recently, the theory has been extended to zero-sum scoring play (Cohensius et al. 2019). Here, we take the approach of cumulative self-interest games, as introduced in a recent framework preprint by Larsson, Meir, and Zick. By adapting standard Pure Subgame Perfect Equilibria (PSPE) from classical game theory, players must declare and commit to acting either ``friendly'' or ``antagonistic'' in case of indifference. Whenever the subtraction set has size two, we establish a tie-breaking rule monotonicity: a friendly player can never benefit by a deterministic deviation to antagonistic play. This type of terminology is new to both ``economic'' and ``combinatorial'' games, but it becomes essential in the self-interest cumulative setting. The main result is an immediate consequence of the tie-breaking rule's monotonicity; in the case of two-action subtraction sets, two antagonistic players are never better off than two friendly players, i.e., their PSPE utilities are never greater. For larger subtraction sets, we conjecture that the main result continues to hold, while tie-breaking monotonicity may fail, and we provide empirical evidence in support of both statements.
format Preprint
id arxiv_https___arxiv_org_abs_2510_24280
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tie-breaking in self interest cumulative subtraction games
Bhagat, Anjali
Kulkarni, Tanmay
Larsson, Urban
Murali, Divya
Combinatorics
Computer Science and Game Theory
91A46, 91A18
Subtraction games have a rich literature as normal-play combinatorial games (e.g., Berlekamp, Conway, and Guy, 1982). Recently, the theory has been extended to zero-sum scoring play (Cohensius et al. 2019). Here, we take the approach of cumulative self-interest games, as introduced in a recent framework preprint by Larsson, Meir, and Zick. By adapting standard Pure Subgame Perfect Equilibria (PSPE) from classical game theory, players must declare and commit to acting either ``friendly'' or ``antagonistic'' in case of indifference. Whenever the subtraction set has size two, we establish a tie-breaking rule monotonicity: a friendly player can never benefit by a deterministic deviation to antagonistic play. This type of terminology is new to both ``economic'' and ``combinatorial'' games, but it becomes essential in the self-interest cumulative setting. The main result is an immediate consequence of the tie-breaking rule's monotonicity; in the case of two-action subtraction sets, two antagonistic players are never better off than two friendly players, i.e., their PSPE utilities are never greater. For larger subtraction sets, we conjecture that the main result continues to hold, while tie-breaking monotonicity may fail, and we provide empirical evidence in support of both statements.
title Tie-breaking in self interest cumulative subtraction games
topic Combinatorics
Computer Science and Game Theory
91A46, 91A18
url https://arxiv.org/abs/2510.24280