# Tagged Questions

The study of competitive and non-competitive games, equilibrium concepts such as Nash equilibrium, and related subjects. Combinatorial games such as Nim are under [tag:combinatorial-game-theory], and algorithmic aspects (e.g. auctions) are under [tag:algorithmic-game-theory].

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### Maxmin and minmax strategies

I was solving for a stable equilibrium in the following 2 player zero sum game. I need to calculate the equilibrium using maxmin and minmax strategies. In this game they should come out to be ...
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### A question about Game Theory Notation in symmetric Games

In Martin Osbourne and Ariel Rubenstien's book A Course In Game Theory (page 20) the authors say that a 2 person game is symmetric the A1 = A2 (both players have access to the same action set) and ...
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### Verifying minimum of a function when second derivative is 0

I was solving for a stable equilibrium in a game. I calculated expected payoff of one of the players which came out to be the function $$E= -4pq + 0.1p + 0.2q + 0.7$$ where p is probability of an ...
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### Blackjack Dice Probability - Odds of winning and where to stand

Hi I'm looking for help/advice in finding the solution to the following problem. Suppose I have a fair $101$ sided dice labelled $0$ to $100$, Your objective is to roll the dice any number of times ...
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### Winner in this game with divisors

I was solving this SPOJ question, which is as below: N wooden pieces (marked with numbers 1 to N) are placed in a transparent bottle. On his turn the first player takes out some piece (numbered x) ...
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### game theory : maximize your score

What is the best way to tackle problem in which two player involved . One can make at most n step , other can m . Both plays optimally . Find out maximum score you can get . e.g. You are give 7 ...
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### Name and related theory for game: “n-th Player to respond wins”

What is the classic name of the game "The N-th player to respond wins"? What are general strategies for the case when the number of total players is not known (or maybe there's only a prior on the ...
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### Nash equilibrium for n players game

There is a question that I am trying to solve but I am not sure about my approach and is hoping I could get some help. Here is the question: There are $n$ companies sharing a water reservoir, let's ...
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### Gaining intuition as to why maximal lotteries use randomness to break general ties

The maximal lottery is a voting system based on choosing an optimal candidate game-theoretically. If a winner isn't clear (there is no condorcet winner), then it will return probabilities as to which ...
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### A coin tossing game with random probabilities

Let $p$ a random variable, uniformed distributed in $[0,1]$. Two player $A$ and $B$ play the following game: Starting from A, a player gets a random value $p(\omega)\in[0,1]$, and he has two choices: ...
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### How to graph a rational reaction set?

In my game theory class, I am asked to graph the rational reaction set for the follow matrix: $\begin{bmatrix} (3,-1) &(-1,-4) \\ (-1,2) & (1,2) \end{bmatrix}$ I am not sure how to graph ...
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### Uniqueness of saddle point solution to zero-sum game

Considering a two player zero-sum game, is a found saddle point solution unique? And if not, are there any conditions under which the saddle point solution is unique?
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### Game theoretic expected utility function with two unknown parameters

I am working on a game theoretic model for my Master's thesis in Political Science, and I have calculated the following expected utility function for player $i$: ${EU}_{i} = 3-12{V}_{i}S$. Both ...
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### Mechanism design with known utilities (game theory)

I'm trying to prove that in an n-party setting, where each party has a private value, the dominant strategy is always to reveal it. I'm assuming that parties only care about monetary payoffs and ...
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### Does exchanging the rows or columns of a matrix game affect the outcome?

This is part of an assignment. I feel like this is a really trivial question or I'm missing some key idea. I'm asked whether exchanging the rows affects a matrix game. I believe it doesn't because the ...
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### “ELO Rating” and how does “TSR Rating” work?

I believe this is the correct forumn as Elo and other ranking systems fall into probability theory, for prediction of chance game outcomes based on previous data. And also as a fitness model for ...
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### Optimizing generalized ternary search

There are $N$ socks numbered $1$ to $N$, one containing a gift. Dave needs to find the sock with the gift. He can ask some questions in order to find that sock: in each question, Dave chooses $2$ ...
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### Game theory - Finding Nash Equilibria

i have to solve these questions. I already came up with a solution. Can anyone look over it and state their opinion? Many thanks in advance :) CHALLENGE I 1. Consider the following game between ...
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### How to prove that the zero sum game's optimal (security) strategy do not change when payoff matrix increase by a constant factor

I am not sure how to construct a proof for something so obvious, can someone give me some pointers on proving the following Suppose a constant K is added to each element of a pay-off matrix ...
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### Best Strategy in a Non-Cooperative Game of Perfect Information (Pure Strategies only)

Suppose there are two players in this game, and each player has $4$ dollars prior to making his move. Each player has as his strategy space the ability to submit an integer number of these $4$ initial ...
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### Game Theory rationalizable strategies that are all the same

Suppose player 1 has strategies u, m, and d, and player 2 has strategies A, B, and C. The strategies A, B and C are all identical (payoff equivalent). Can any of them be eliminated using the ...
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### Playing rock paper scissors over online chat.

Is there a way to play rock, paper and scissors fairly over internet chat? By this, I mean that both players cannot play their hands simultaneously, one of them has to go first and the second player ...
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### What is the optimal losing move?

I had a hard time trying to find the best-suited stackexchange site to ask this question. I'm still not sure whether this is the right place, so please guide me to the right one if you think this is ...
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### Optimal strategy to escape spotlight

Here is the setup. A prisoner is being held in the center a circular yard with radius $r$ and can run in any direction at some velocity $v$, there is a spotlight which illuminates a line on the circle ...
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### One Million Proficiency Efficiency Calculations

I have been playing the "Million" game on my apple device after discovering it through the trending applications in the search function. After beating the game I began to wonder to myself if there was ...
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### Find the mixed strategy Nash equilibria in the investment race

This is Exercise 35.2 in Rubinstein's "A Course in Game Theory". This problem is very difficult. The lecturer gave us the answer but it's very hard to understand. I paste the problem here: Two ...
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### Coin flipping game - probability and game theory

I'm exercising for a test and I've been trying to solve this problem. John bets 1 or 2 dollars before flipping a coin. If the result is heads, he wins the sum he has bet. If the result is tails, he ...
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### Is there any winning strategy? 2015 and Game with marbles!!!

Two players, Alex and Brad, take turns removing marbles from a jar which initially contains 2015 marbles. Assume that on each turn the number of marbles withdrawn is a power of two. If Alex has the ...
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### Making sense of an Expected Utility of a Mixed-strategy Profile definition

I came across a definition of Expected Utility of a Mixed-strategy Profile in Brown's and Shoham's "Essentials of Game Theory: A Concise, Multidisciplinary Introduction" where: "Given a normal-form ...
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### Maximize the Earning

There are two thieves with a total of 1 billion ($10^9$) dollars in a bank vault. Now they must decide how to divide the booty. But there is one problem: the thieves have only $M$ minutes to leave the ...
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### How to divide the money based on the below conditions? [closed]

Two cheeky thieves have collectively decided to rob a bank. They have carefully counted a total of exactly $100$ dollars in the bank vault. Now they must decide how to divide the booty. But there is ...
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### Shapley values as a hash/compression of a game

Computing a Shapley value, we are mapping the set of coalition games on $N$ to a vector of $N$ elements: $$\phi: \; \mathbb{R^{2^N}} \to \mathbb{R}^N$$ In a sense, this is compression, or more ...
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### Multiplying Single Digit Numbers to Get Product >1000

This is yet another Alice and Bob problem. Alice and Bob are playing a game on a blackboard. Alice starts by writing the number $1$. Then, in alternating turns (starting with Bob), each player ...
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### Good books to learn Combinatorial Game Theory?

I am currently doing my IB Diploma and we are supposed to make an extended essay on a subject of our choice- and i chose math. my research question is- "how to derive a perfect strategy to always win ...
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### Game theory: solutions concepts if each player has different utility

Assuming, I have a network game (where the players are e.g. users in a network), how is it possible to model user-specific a-priori information (which results in different utility functions for each ...
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### Question about usage of $\leq$ in definition of Nash equilibrium

Quick definition: Given $g$, a strategy N-tuple $u^* = (u_1^*,...,u^*_N)$ is said to be a Nash equilibrium if: $$J_i(u_i^*, u^*_{-i}) \leq J_i(u_i, u^*_{-i}), i \in N$$ where $J$ is ...
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### What is the quickest way to find Nash equilibria in two player bimatrix game?

Suppose the cost/penalty matrix of a game is given as: $$M = \begin{bmatrix} (-5,-5) & (0,0) \\ (0,0) & (-3,-3) \end{bmatrix}$$ Then the game as two equilibria $(u_{11},u_{21})$ and ...
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### In what ways would a course on convex optimization be useful in game theory?

From talking to several other people in the past, and referencing Quora, it seems that convex optimization is really a tiny subset of game theory in that it only models the behavior of one single ...
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my text defines player set as: In N-player game $g$, each non-terminating node is partitioned into $N+1$ sets $g^0, ... g^N$. These are player sets. However it makes no attempt to identify ...
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### Devising a method to arrive at a square only being able to move right and up

I was recently presented with a problem where I have a 10x10 grid and a marker that starts at position (1, 1). Two players are able to manipulate the marker by moving it as far right, or (exclusive) ...
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### Reducing TIC-TAC TOE State Space by using Symmetry in Artificial Intelligence

Im learning Heuristics in AI.I see that for brute force search there are 9! states.But the textbook says that first 3 levels are reduced by symmetry.How does that work?
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### A question in Osborne-Rubinstein A course in game theory,

I am having trouble with Rubinstein's electronic email game (proposition 83.1) in the textbook(first edition). My question: Line 7 starting from the "proof", "...player 2's expected payoff is at ...
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### How many legal states of chess exists?

I have a fairly simple question. How many legal states of chess exists? "Legal" as in allowed by the rules and "state" as an unique configuration of the pieces. I'm not asking for the number of ...
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### numerical solution for nash equillibrium

I have the following setup. $\pi_1=f_1(q,r)$ and $\pi_2=f_2(q,r)$ are the real valued payoff/profit functions of the two players. Player 1 gets to pick $q$ and player 2 gets to pick $r$. I also know ...
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### Probabilities in this blackjack variation

Let's say I play blackjack (52 cards, figures count for 10, aces count for 1 or 11) and alone (no dealer). The cards I use for one particular game are always removed at the end of that game and won't ...
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### “Composition” property in cooperative game theory?

I am trying to find a property which can help to analyse the composition of a cost/profit division and which allocation rules (e.g., Shapley value or nucleolus) would satisfy it. In short, the idea ...
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### Tzaloa 2015 game problem (piles with $1,2,4 \dots 2^{19}$ coins each)

We have $20$ piles with $1,2,4,8\dots 2^{19}$ coins repectively and two players. In each turn a player must select five piles that have at least one coin and remove exactly one coin from each. Player ...
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### Why does the 1st player in this subset take-away game always have a winning strategy?

This is a HW problem of mine that I cannot, for the life of me, figure out. There is a take-away game where there are a number of elements A, and the person that wins is that last person to remove a ...
Consider a game for two players, say "Player A" and "Player B". The two sets of strategies are denoted by $A$ and $B$, available to the players. Consider a symmetric situation where the players have ...
As explained here, the average distance or 'travel' of a random walk with $N$ coin tosses approaches: $$\sqrt{\dfrac{2N}{\pi}}$$ What a beautiful result - who would've thought Pi was involved! ...