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In many combinatorial games, one can prove that the first player wins under best play using a simple but non-constructive argument called strategy-stealing. This work is about the complexity behind these proofs: how hard is it to actually…

Data Structures and Algorithms · Computer Science 2019-11-19 Greg Bodwin , Ofer Grossman

Poset games are a class of combinatorial game that remain unsolved. Soltys and Wilson proved that computing wining strategies is in \textbf{PSPACE} and aside from special cases such as Nim and N-Free games, \textbf{P} time algorithms for…

Combinatorics · Mathematics 2021-01-26 Alexander Clow , Stephen Finbow

In an all-pay auction, only one bidder wins but all bidders must pay the auctioneer. All-pay bidding games arise from attaching a similar bidding structure to traditional combinatorial games to determine which player moves next. In contrast…

Computer Science and Game Theory · Computer Science 2015-05-15 Michael Menz , Justin Wang , Jiyang Xie

The game of i-Mark is an impartial combinatorial game introduced by Sopena (2016). The game is parametrized by two sets of positive integers $S$, $D$, where $\min D\ge 2$. From position $n\ge 0$ one can move to any position $n-s$, $s\in S$,…

Combinatorics · Mathematics 2025-04-01 Gabriel Nivasch , Oz Rubinstein

We study zero-sum games, a variant of the classical combinatorial Subtraction games (studied for example in the monumental work "Winning Ways", by Berlekamp, Conway and Guy), called Cumulative Subtraction (CS). Two players alternate in…

Combinatorics · Mathematics 2020-02-14 Gal Cohensius , Urban Larsson , Reshef Meir , David Wahlstedt

In this paper, we introduce a variant of Francis Su's "Game of Cycles," that we call "Cycles with Sources." The only change to the rules is permitting nodes to be sources, while sinks are still prohibited. Despite this minor change in the…

Combinatorics · Mathematics 2023-09-13 Vigyan Sahai , Ravi Tripathi

By resorting to the vector space structure of finite games, skew-symmetric games (SSGs) are proposed and investigated as a natural subspace of finite games. First of all, for two player games, it is shown that the skew-symmetric games form…

Computer Science and Game Theory · Computer Science 2017-12-11 Yaqi Hao , Daizhan Cheng

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…

Combinatorics · Mathematics 2026-01-22 Anjali Bhagat , Tanmay Kulkarni , Urban Larsson , Divya Murali

A combinatorial game is a two-player game without hidden information or chance elements. The main object of combinatorial game theory is to obtain the outcome, which player has a winning strategy, of a given combinatorial game. Positions of…

Combinatorics · Mathematics 2025-11-27 Kengo Hashimoto

The most important factors which contribute to the efficiency of game-theoretical algorithms are time and game complexity. In this study, we have offered an elegant method to deal with high complexity of game theoretic multi-objective…

Computer Science and Game Theory · Computer Science 2015-03-13 Mahsa Badami , Ali Hamzeh , Sattar Hashemi

We find the winning strategy for a class of truncation games played on words. As a consequence of the present author's recent results on some of these games we obtain new formulas for Bernoulli numbers and polynomials of the second kind and…

Combinatorics · Mathematics 2014-06-10 Gábor Hetyei

Simple stochastic games are two-player zero-sum stochastic games with turn-based moves, perfect information, and reachability winning conditions. We present two new algorithms computing the values of simple stochastic games. Both of them…

Computer Science and Game Theory · Computer Science 2015-07-01 Hugo Gimbert , Florian Horn

This paper provides effective methods for the polyhedral formulation of impartial finite combinatorial games as lattice games. Given a rational strategy for a lattice game, a polynomial time algorithm is presented to decide (i) whether a…

Combinatorics · Mathematics 2011-05-30 Alan Guo , Ezra Miller

Combinatorial Game Theory has also been called `additive game theory', whenever the analysis involves sums of independent game components. Such {\em disjunctive sums} invoke comparison between games, which allows abstract values to be…

Combinatorics · Mathematics 2021-01-29 Urban Larsson , Richard J. Nowakowski , Carlos P. Santos

For impartial games $\Gamma$ and $\Gamma'$, the Sprague-Grundy function of the disjunctive sum $\Gamma + \Gamma'$ is equal to the Nim-sum of their Sprague-Grundy functions. In this paper, we introduce $p$-calm subtraction games, and show…

Combinatorics · Mathematics 2021-01-13 Yuki Irie

In 1901, Bouton proved that a winning strategy of the game of Nim is given by the bitwise XOR, called the nim-sum. But, why does such a weird binary operation work? Led by this question, this paper introduces a categorical reinterpretation…

Combinatorics · Mathematics 2025-11-17 Ryuya Hora

Subset take-away is a two-player game involving a fixed finite set A. Players alternate choosing a proper, non-empty subset of A, with the condition that one may not name a set containing a set that was named earlier. A player unable to…

Combinatorics · Mathematics 2016-05-05 J. Daniel Christensen , Mark Tilford

Subtraction games are a classical topic in Combinatorial Game Theory. A result of Golomb~(1966) shows that every subtraction game with a finite move set has an eventually periodic nim-sequence, but the known proof yields only an exponential…

Combinatorics · Mathematics 2026-03-18 Anjali Bhagat , Urban Larsson , Hikaru Manabe , Takahiro Yamashita

Compositional Game Theory is a new, recently introduced model of economic games based upon the computer science idea of compositionality. In it, complex and irregular games can be built up from smaller and simpler games, and the equilibria…

Computer Science and Game Theory · Computer Science 2017-11-22 Neil Ghani , Clemens Kupke , Alasdair Lambert , Fredrik Nordvall Forsberg

Given two finite sets of integers $S\subseteq\NNN\setminus\{0\}$ and $D\subseteq\NNN\setminus\{0,1\}$,the impartial combinatorial game $\IMARK(S,D)$ is played on a heap of tokens. From a heap of $n$ tokens, each player can moveeither to a…

Discrete Mathematics · Computer Science 2015-11-10 Eric Sopena