Questions tagged [nash-equilibrium]

A basic solution concept in game theory that requires each player to select their best response to the strategies chosen by others.

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1answer
129 views

Effect of bounding action space on the set of equilibria

Suppose $N$ players play a game, where each player's action space is $[0,1]$. Each player has an identical continuous utility function $u:[0,1]\times [0,1]^{N-1}\rightarrow\mathbb{R}$, where the first ...
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1answer
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How to find pure strategy NE if you have a n X n matrix (n players) [closed]

Consider the down below which I have trouble with solving. I am not used to find NE for n players, but rather for a simple $2 x 2$ matrix or $3 x 3$, but how does one find NE when you have N players? ...
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26 views

Cournot nash equilibrium

The market demand for a good is described by the inverse demand function $P(Q) = 120 - Q $ where $Q$ is total quantity demanded and $P(Q)$ the market price. Two firms $i =1,2$ have identical cost ...
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33 views

Pure Nash equilibrium in bidding game?

According to the answer key for a problem set, there is no pure strategy Nash equilibrium in the following problem. Yet I can't see why not. Could it be an error in the answer key? Here's the problem: ...
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2answers
297 views

Showing existence of a Nash equilibrium in pure strategy

Consider a game with $N$ players, each indexed by $i=1,...,N$. Every player $i$ has to choose a $J\times 1$ vector of actions $a_i\equiv (a_{i,1},...,a_{i,J})$ where each $a_{i,j}$ can be zero or one. ...
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2answers
485 views

Auctions and finding nash equilibrium of a dynamic game

Suppose we have a sequential version of an Auction game: • Player 1 places a bid. • Player 2 observes player 1’s bid, then places a bid. • The player with the highest bid wins the item at auction. • ...
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1answer
71 views

Characterising a set of outcomes containing the collection of pure strategy Nash equilibria

Consider a game with $N$ players, each indexed by $i=1,...,N$. Every player $i$ has to choose a $J\times 1$ vector of actions $a_i\equiv (a_{i,1},...,a_{i,J})$ where each $a_{i,j}$ can be zero or one. ...
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0answers
72 views

Nash equilibrium with three players

Consider the game below played by three players. Player 1 chooses one of the rows (T vs B). Player 2 chooses one of the columns (L vs R). Player 3 chooses one of the three tables (A vs B vs C). Each ...
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1answer
73 views

Bayesian Nash Equilibrium in a Duopoly Cournot Competition

I am having a hard time to solve a Bayesian Nash equilibrium game in a duopoly cournot competition setting. So, I have two firms with given production quantities, let's say $q_1$ and $q_2$ (i.e., not ...
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2answers
64 views

Game Theory: Continuity in equilibrium profits?

Consider 2 agents $A_i$. $A1$ moves before agent $A2$. Each of their utility functions is continuous in each agents' decision $0<s_i\in \mathbb{R}$ and a parameter $x$. Additionally, each agent's ...
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1answer
37 views

Strong sequential equilibria and the existence of others

I am working on the following game and I have to find all strong sequential equilibria here. I determined that here any belief derived from a fully mixed strategy gives a distribution (1/2, 1/2) over ...
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1answer
45 views

If a best-response dynamic converges, does it converge to a Nash equilibrium?

Consider a game with a finite number of players and finite action space. Suppose we consider a sequential iterative game-playing process in which, in each period, players myopically select actions ...
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How to find an optimal strategy in an auction?

I have asked this question in mathematics forum as well but since I have not recieved an appropriate answer yet, I ask it here as well. Consider an auction of sculptures by four artists: A, B, C and D....
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1answer
345 views

Relaxing the notion of Nash Equilibrium

Consider a game with $N$ players, each indexed by $i=1,...,N$. Every player $i$ has to choose a $J\times 1$ vector of actions $a_i\equiv (a_{i,1},...,a_{i,J})$ where each $a_{i,j}$ can be zero or one. ...
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1answer
39 views

Differences between best response, dominant strategy and Nash equilibrium

I can't seem to get the differences of these terms. I watched this video that has the differences of best response and Nash equilibrium: But then I heard about dominant strategies from another video ...
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1answer
43 views

Can't find the SPNE

For a homework assignment, I need to find the subgame perfect equilibrium. The assignment asserts that there is only one subgame perfect equilibrium in this problem, but I am stuck between two ...
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2answers
61 views

Is there really a Nash equilibrium in this example?

I was watching this video on Coursera and worked out the example before the solution was presented. The example begins at 4:20 The presenter says that the Nash ...
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1answer
29 views

How to set up the payoffs properly for a division of labor game

I'm admittedly a novice when it comes to game theory (currently a few lectures into Yale's intro course lectures), so hopefully people will indulge me what may be a dumb question. I was trying to ...
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2answers
94 views

Does Nash Equilibrium predict the existence of vaccine reluctance?

I was listening to a lecture on Nash Equilibrium, which stated that a Nash Equilibrium by definition occurs at a point that no players in the game have an incentive to change their strategy - everyone ...
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0answers
40 views

Will the outcome of a game always be a Nash Equilibrium?

Consider this game between two players. This game has two Nash Equilibria: (U, C) and (D, R). Suppose we ask the players to play this game once. What should our prediction of the game's result be? If ...
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1answer
39 views

Rationalizable strategies and Weak Dominance

Can I find the rationalizable strategies for a game where none of the players has strict dominance but only weak dominance?
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1answer
44 views

symmetry of equilibria with heterogeneous players

I have a question about game theory terminology. I am working on a model in which players are heterogeneous in two dimensions, and there are four types of players. For example one type of players ...
4
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1answer
112 views

Finitely repeated Prisoner’s Dilemma with switching cost

I'm doing this finitely repeated Prisoner's dilemma with switching costs but I have trouble showing the fact that $\varepsilon$ had to be $1 < \varepsilon < 2$. I do see why and that it is a ...
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0answers
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Fehr-Schmidt, Ultimatum game, Subgame-Perfect Nash Equilibrium

I'm studying the different variations of the ultimatum games. I've spent some time on this following game: Assume now that each player does not only care about the amount of money she receives, but ...
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1answer
49 views

Subgame-perfect Nash equilibrium perfect information

This might be a stupid question but please bear with me. I'm trying to solve this game but I'm in doubt on how to represent the strategy profile of the game. The game looks like this in extensive-form....
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1answer
66 views

Set of rationalizable strategies for this 4 x 4 matrix

I would like to find the set of rationalizable strategies for this 4x4 game: The first thing I did was try and find all PSNE. I found two, the ones I bolded. Thus, my answer to this question is that ...
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1answer
216 views

Mixed Strategy Nash Equilibrium for this particular 3x3 matrix

Suppose I am given the following matrix: I would like to find all MSNE I started by doing the double underline method to find any PSNE. I discovered that none exist. I then looked at which strategies ...
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1answer
59 views

A question about Nash Equilibrium

I have some trouble with Nash Equilibrium. The specific question as follows. Suppose that there are $2N$ people in the village, of which $N$ residents live in the first district, and each person ...
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1answer
53 views

Finding pure-strategy subgame-perfect Nash equilibria

I'm interested in finding the pure-strategy subgame-perfect Nash equilibria of the game below. What is confusing me is that after player A chooses between reducing and not reducing his end payoffs, ...
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1answer
161 views

Mixed Strategy Bayesian Nash Equilibrium

There was an exercise question regarding two players with two types each in a game theory class. The two players were assigned to do a team project together. The utility from doing the team project is ...
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3answers
310 views

SPNE of a normal form game

If we have a sequential game which is equivalent to a simultaneous move game because of its information structure, then the NE we find are also SPNE?
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1answer
48 views

Finding Nash Equilibrium

Where would the Nash equilibrium lie in the pictured scenario? Whats confusing me is that both persons best response changes depending on the choice of the other person (there is no dominant strategy)....
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2answers
99 views

Subgame Perfect Equilibrium for Pure and Mixed strategy

In a game theory textbook there is something similar to the table below where there is one pure strategy nash equilibrium and multiple mixed strategy nash equilibria. It is a simultaneous game with ...
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0answers
33 views

Nash in demand functions!

I am searching for some types of games that are played in linear demand functions. Altough I hear that there is a vast literatrure for games that are played in the intercept or the slope of the demand ...
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2answers
68 views

In a game with alternating moves and complete information, the Nash equilibrium cannot be a non-trivial mixed equilibrium?

Where I can find a simple proof for this fact? For example, a trivial bimatrix game with alternating move has the following payoff matrix: \begin{array}{|c|c|c|} \hline & 1 & 2 \\ \hline U &...
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1answer
89 views

Mixed Strategies in Bayes Nash Equilibrium (Bayesian Battle of the Sexes). Shouldn't it depend on $p$?

I have a question about calculating mixed strategies in a Bayes Nash Equilibrium in a simple 2-player bimatrix game. To demonstrate the issue, consider ``Bayesian Battle of the Sexes.'' Suppose P1 ...
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2answers
105 views

Cournot oligopoly - first-order condition

I am reading an article that has this description of the first-order condition for a Cournot n-firm game: Take $P(Q) = Q^{-1}$, $\pi_i(q_i, Q) = (Q^{-1} - c_i)q_i$. Then the first-order condition for ...
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2answers
116 views

How can I build a fixed point theorem argument in pure strategies?

To begin with, I am recalling the Banach Fixed Point Theorem. Let $(X,d)$ be a non-empty complete metric space with a contraction mapping $T:X\to X$. Then $T$ admits a unique fixed-point $x^*$ in $X$ ...
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2answers
120 views

Pure-Strategy Bayesian Nash equilibrium with general common prior

I'm doing a problem set on the subject of Bayesian Nash equilibrium. I'm asked to find the pure-strategy BNE of the following. I've calculated to matrix shown below. My first concern is if I've ...
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4answers
158 views

Doubt about Mixed Strategy Nash Equilibrium

Here's the video I will be referring too. Now I am a complete beginner in game theory, so sorry if this sounds like a stupid question, but why would a player want to balance out the payoffs of another ...
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1answer
262 views

Nash Equilibrium for n-shops Location Game

So if two ice cream shops were to be placed in the location $[0,1]$, inorder to maximize their own pay offs, they both would finally come to the location $[\frac{1}{2}, \frac{1}{2}]$. This is also the ...
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2answers
114 views

Stag Hare inefficient Nash Equilibrium and level-K thinking

Two players $i,j$; both have two strategies $\{h,s\}$. The payoffs vector of $i,j$: $u(h,h)=(5,5)$ (if both players choose $\{h\}$ then $i$ receives 5 and $j$ receives 5) $u(h,s)=(10,0)$ $u(s,h)=(0,10)...
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1answer
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Interpretation of Nash equilibrium as a potential stable point of a dynamic process

I'm reading an article called "The Nash equilibrium: A perspective" by Holt and Roth, and the below paragraph caught my attention. When the goal is prediction rather than prescription, a ...
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2answers
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Can mixed strategies actually predict behaviour of rational actors in non-constant sum games?

I understand how the concept of the mixed NE (mathematically) works. But I don’t understand how we can expect players to behave in a way that would arrive at such an equilibrium. Consider the ...
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2answers
66 views

Does the value of a pure strategy Nash equilibrium(if exists) equal the value of the mix strategy Nash equilibrium in two-person zero-sum game?

Given a two-person zero-sum game, a mixed strategy Nash equilibrium always exists and all such equilibria have the same value. A pure strategy Nash equilibrium, however, may not exist. My question is:...
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1answer
60 views

Existence of Symmetric Pure Strategy Equilibrium

I have 2 symmetric players $A$ and $B$. Each of them has 2 decision variables $x_i\in[0, \beta]$ and $y_i\in[0,1]$, where $i\in\{A,B\}$. Their payoff functions are symmetric, i.e., if you swap the ...
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2answers
93 views

NE equilibrium with lobbying of cournot producers

I have had an exam (exam is now past and submitted, but I want to now understand the solution without waiting) with the following questions: GAME Consider two firms playing the following two-stage ...
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1answer
54 views

Find value of $\beta$ for which there is a strictly dominant strategy

The question is as such: $N$ firms are lobbying for subsidies. Let $h_i$ be the number of hours spent by form $i$ for lobbying, with cost $wh_i^2$ where $w$ is a fixed constant. The subsidies granted ...
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1answer
71 views

(Why) was von Neumann not a fan of the Nash equillibrium concept?

Charles A. Holt and Alvin E. Roth's The Nash equilibrium: A perspective notes: "In a personal communication with one of the authors, Nash notes that von Neumann was a “European gentleman” but was not ...
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1answer
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Why do we need a restriction of a game to prove the given statement?

Consider a game $G$. We have to prove that is $s$ is a Nash Equilibrium of $G$, then it is also a Nash Equilibrium of the game formed by removing strictly dominated strategies of $G$. I looked at the ...