Combinatorial game theory (abbreviated CGT) is the subfield of combinatorics (not traditional game theory) which deals with games of perfect information such as Nim and Go. It includes topics such as the Sprague-Grundy theorem and is tangentially related to the Surreal Numbers.

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Is it true that we can get zero for all $(x,y,z)\in\mathbb{N}^3$?

There are three distinct positive integers $x$, $y$, and $z$. We can choose two numbers $a,b\in\{x,y,z\}$, where $b\leq a$, then replace $b$ by $2b$ and replace $a$ by $a-b$. Is it true that there ...
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31 views

Create the most 'stressful' tennis game ever!

Some games, such as tennis, use a complicated points system (point, game, set, match; with deuces and tie-breaks) for what would otherwise be an extremely simple and monotonous game. The main reason, ...
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42 views

explaining the pattern

I have been given the following math puzzle: you are given a matrix that is filled by the following rule: every cell i,j is evaluated by taking the lowest non-negative number that is not present in ...
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1answer
26 views
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Reducing an I-optimal problem to a Pareto-optimal problem

Given a set $\textbf y\subset\mathbb R^2$, let $y = (y_1,y_2), y'=(y'_1,y'_2)\in\textbf y$ be elements of that set, let $\alpha_{min}\in\mathbb R$, $\alpha_{min}<1$, $\alpha_{max}\in\mathbb R$, ...
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39 views

Combinatorial approach to calculate determinant

Suppose you have set of $n*n$ matrices with entries from the set $\{1,-1\}$. Then what can be the maximum determinant which you can obtain from such type of matrices.
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1answer
489 views

Optimal Tic Tac Toe algorithm without lookahead

Is there any algorithm for tic tac toe that does not rely on a lookahead algorithm that is perfect for any sized boards? Edit: For boards larger than $3 \times 3$, we have to find the best move for ...
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1answer
24 views

Biobjective optimisation, pareto non-domination

Ok, so, I have a function $f_I(y_1, y_2) = \max\{\alpha y_1 + (1-\alpha)y_2:\alpha\in[\alpha_{min},\alpha_{max}]\}$ that I'm trying to minimise, and I'm asked to find, amongst a set of vectors $y$, ...
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19 views

most competitive game formula

I am creating a game and have variables that I need to figure out. So the game will consists of a number of available options. I'm trying to find how many picks per player and number of players will ...
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1answer
217 views

Bidding Tic Tac Toe

In regular tic tac toe, both the players get alternate chances. This is a variant of that. Player $A$ has $\$x$ amount and player $B$ has $\$y$ amount as initial balance. Assume that $y>x$. Both ...
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26 views

Coloring the balls

Bob and Alice are playing a game. Initially they have balls of black and white color arranged together in a line. Rules of the game are as follows: 1.They start the game by going from right to left ...
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11 views

Linearization bounds on 0-1 quadratic problems

What are the best linearization methods for approximating the following constrained 0-1 Quadratic problem, where $Q \in \mathbb{R}^{n\times n}$ and $k$ is an integer $1\leq k \leq n$ $$ \max ...
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2answers
174 views

Why does the theory of the game Nim use binary digital sums?

So I was reading "Graphs and their uses" by Oystein Ore and I came across a section about the game called Nim. Now the author takes as granted the binary digital sums as a way of solving the game. The ...
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1answer
457 views

Calculating the Shapley value in a weighted voting game.

Given a special case of WVG (Weighted Voting Game) of $a$ 1s and $b$ 2s and a quota q, $ [q:1,1,1,1..1,2,2,..2] $. I need help with calculating the Shapley value of a player with a weight of $2$ and a ...
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1answer
86 views

Why does strategy-stealing not work for Go?

The related Wikipedia article states: In Go passing is allowed. When the starting position is symmetrical (empty board, neither player has any points), this means that the first player could steal ...
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2answers
227 views

Game to maintain distinct number of balls in glasses

There are $n$ glasses, containing $n+1,n+2,\ldots,2n$ balls, respectively. Two players $A$ and $B$ play a game, alternately taking turns with $A$ going first. In each move, the player must choose some ...
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3answers
306 views

Why are the surreals considered “recreational” mathematics?

One of my college math professors once remarked to me that it was interesting that John Conway's two "biggest" contributions to math were both recreational: the Game of Life and the Surreals. No one, ...
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3k views

The Ring Game on $K[x,y,z]$

I recently read about the Ring Game on Mathoverflow, and have been trying to determine winning strategies for each player on various rings. The game has two players and begins with a commutative ...
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1answer
30 views

Modified parcheesi game

A "modified Parcheesi" game starts with the following position: First $x$ flips a fair coin. If heads he can move two spaces or pass. If tails he can move one space or pass. If he occupies the ...
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Combinatorics- related to poker

In how many ways can a straight flush be dealt ,if two of the cards originally dealt must be discarded and replaced but not if all the 5 cards are clubs ?
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1answer
80 views

Can the wolves catch the hare?

Say you have 7 positions. 1 Hare and two Wolves in the following starting positions:    H o     o W   W  o   o The hare can take a step of size 2. The ...
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371 views

“Infinito”, a combinatorial game with infinite width game-tree

I recently designed a combinatorial game (sequential game of perfect information) with an infinite branching factor, that is it has a game-tree of infinite width. I'm wondering how is it possible to ...
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39 views

Recreational chess questions based on the knights

I basically know whether the following statements are true, but I would like to know how they are proved. A knight kept anywhere on an empty chess board can not reach its adjacent square in exactly ...
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490 views

The expected outcome of a random game of chess?

Imagine a game of chess where both players generate a list of legal moves and pick one uniformly at random. Q: What is the expected outcome for white? 1 point for black checkmated, 0.5 for a ...
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1answer
33 views

A 2 Player Pure Strategy Game

There are two players each has $n$ balls. At the same time they distribute their balls among $m$ boxes. For each box 1 point is given to the player with more balls and zero points to other one (When a ...
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38 views

Is this proposition posible? [duplicate]

In a board, you have $13$ White round pieces, $15$ Black round pieces, and $17$ Red round pieces. In each round you can choose two different color pieces and change them with two other pieces of ...
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145 views

Winning strategies in multidimensional tic-tac-toe

This question is a result of having too much free time years ago during military service. One of the many pastimes was playing tic-tac-toe in varying grid sizes and dimensions, and it lead me to a ...
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Prime number building game

Players $A$ and $B$ choose digits $(0, \dots , 9)$ turn by turn and build number by concatenating the digit they chose to the end of the number. Player $A$ starts by picking the first (one-digit) ...
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44 views

Counting all possible legal board states in Quoridor

Ignoring pawns there are 1,375,968,129,062,134,174,771 possible ways to place 0 to 20 walls on the Quoridor board, as answered here. Ignoring walls there are 81 * 81 = 6410 ways to place the two ...
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2answers
257 views

traveling salesman with pairs of cities, without return and with given start and end cities

I am looking for the name of the following two problems, and an approach to solve them. Problem#1: given N nodes, find the shortest path starting at a given start node and ending at a given end node, ...
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2answers
26 views

prove that if $n=k$ then white has a winning strategy in $S_{n,k}$.

Black and white play sequentially the game $S_{n,k}$ with $k,n\in \mathbb N \space 0\leq k\leq n$ the game board consists of all subsets $A\subseteq\{1,2,...,n\}$ such that $1\leq |A|\leq k$. every ...
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2answers
81 views

Counting problem about pirates and gold coins [duplicate]

Five pirates find a cache of 500 gold coins. They decide that the shortest pirate will serve as the bursar and determine a distribution of the coins however he sees fit, and then they all will vote. ...
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1answer
29 views

Game removing tokens on number line

A two-player game begins with $k<2^n$ tokens placed at point $0$ on the number line spanning $[0,n]$. Each round, player $A$ chooses two disjoint, non-empty sets of tokens $X,Y$. Player $B$ takes ...
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Combinatorics For $4$ Pool Balls

There lie $4$ pool balls on a pool table: two striped and two plain. Two of the pool balls are selected at the same time, at random. Given that one of the selected balls is striped, what's the ...
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1answer
26 views

Game picking cards so that sum is divisible by $25$

Adele and Bryce play a game. There are $50$ cards, numbered $1,2,\ldots,50$. They take turns alternately picking a card, with Adele going first. If at the end, the sum of the numbers on Adele's cards ...
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3answers
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Card Game Probability 13 Card Hand

Me and my friends play a four person poker style card game. Each person is dealt 13 cards, and it is a standard trump card game. Now, as the standard, a five card flush beats a five card straight, but ...
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2answers
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Gomoku on an infinite big board

I always used to play Gomoku in school on paper, and if we reached the edge of the field, we just put another one at that side. And now I just saw that black can always win on 1 15x15 board. But what ...
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2answers
284 views

Converting a Gomoku winning strategy from a small board to a winning strategy on a larger board

Gomoku is the game where Black and White take turns placing stones of their own color, and the winner is the player who first gets five of their own stones in a row. Black moves first. In Gomoku on ...
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1answer
26 views

Proof sprague-grundy value is 0 if and only if it is losing position

So, i take this game theory module this summer, and i encountered this exercise problem, i tried to do this by induction by have terminal position (grundy-value = 0) as base case, but can't figure out ...
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1answer
84 views

Game replacing two numbers by mean

Alicia and Bart plays a game. Alicia first writes $100$ real numbers on the board. After that they move alternately; Bart goes first. In every move, the player chooses two numbers, erases them, and ...
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Game placing numbers in increasing order

Let $k\leq m\leq 100$ be positive integers. Aaron and Britney play a game on a $1\times m$ board, using $100$ paper pieces numbered from $1$ to $100$. The game has $k$ turns. In each turn, Aaron ...
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1answer
43 views

Game of polygons

Initially, there is a polygon with N vertices drawn in the plane. The polygon is strictly convex, i.e., each internal angle is strictly smaller than 180 degrees. The vertices of the polygon are ...
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1answer
168 views

What to do with a random variable when we know its mean and variance but does not know which distribution it is?

Let Y be a random variable with mean μ and variance σ^2 where the support is (0, ∞). Suppose you are offered to play a game where you choose a number z between (0, ∞). If a realization of the random ...
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1answer
81 views

Commutative Algebra and Game Theory

Is there any relationship between commutative algebra and game theory? For example, have any tools in commutative algebra been applied to game theory? A text or reference would be ideal, but I'd be ...
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1answer
65 views

Characteristic 3 analogue of nimbers?

Finite nimbers are a way of turning the natural numbers (finite ordinals) into a characteristic 2 field. Addition in this field is found by writing the numbers in binary and adding without carry, ...
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5answers
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Game Theory - First move vs second move advantage?

This question came up in a lunchtime discussion with coworkers. None of us are professional mathematicians or teachers of math, and we weren't sure how to get the answer. I apologize in advance if my ...
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Eating chocolate game on grid

Given is a chocolate of size $m\times n$. Anne and Birgitte plays a game, with Anne starting. In each turn, the player has to divide the chocolate into two rectangular parts along the lines, and eat ...
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What is the largest value one can get in game 2048 without new tiles appear

This is a simplified version of the famous game 2048. Given a 4x4 grids with some values chosen from {0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048}. A value of 0 indicates that the position in ...
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1answer
94 views

Counting all possible board positions in Quoridor

I'm trying to figure out how many possible board positions there are for the game Quoridor. I think sorting out the legal positions from the illegal positions will be difficult, so to start I'm trying ...
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1answer
69 views

Pigeon-hole principle applied to the game of tic tac toe

In a game of tic tac toe, noughts and crosses are drawn inside an unoccupied cell of a 3 x 3 matrix by two players I, II in alternating moves. Player I draws crosses and Player II draws noughts. The ...
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1answer
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Nim Sum Game Variant

Suppose there are black and white balls in a box. The initial number of white balls is m and the initial number of black balls is n. This is a two player game. Each player can do the following taking ...