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2 votes
0 answers
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Complexity of deciding whether a given payoff vector can be achieved by some mixed strategy profile in a normal form game

Note that this mixed strategy profile does not need to be a Nash equilibrium. I'm mostly looking for references, as I assume the answer is known, but my searches have only found results about Nash ...
Lisa Henderson's user avatar
0 votes
0 answers
70 views

Undecidability of games with limited hidden state

Surprisingly, approximate win probability for one-player games with randomness and 3 bits of hidden state (in addition to non-hidden state; rational transition probabilities) is uncomputable. Question:...
Dmytro Taranovsky's user avatar
3 votes
1 answer
249 views

Which 1-player games are EXPTIME-complete? Also, are there any known games that are EXPSPACE-complete?

I noticed a lot of 1-player games have been shown to be NP-Hard, like Pac-Man, The World's Hardest Game, Tetris, etc. For PSPACE-Complete, I noticed that Wikipedia listed these 1-player games: It is ...
edit's user avatar
  • 33
0 votes
1 answer
233 views

What Complexity Class is this? Is this already known?

Let's call this the Path Game. For this example, lets imagine a 16x16 grid: Some of the squares in this grid are "deadly." If you step on it, you must restart and try to go over again. We ...
Bapcap's user avatar
  • 21
11 votes
0 answers
206 views

Is 4-in-a-row PSPACE-complete?

This paper by Laurens Kuiper shows that axis-parallel k-in-a-row is PSPACE-complete in complexity for k ≥ 5, but leaves the question open for k = 4. Has there been any research progress on this ...
user76284's user avatar
  • 682
13 votes
3 answers
1k views

A game on several graphs

Consider the following game on a directed weighted graph $G$ with a chip at some node. All nodes of $G$ are marked by A or B. There are two players Alice and Bob. The goal of Alice (Bob) is to ...
Alexey Milovanov's user avatar
10 votes
1 answer
516 views

What is the complexity of this game?

This is a generalization of my previous question. Let $M$ be a polynomial-time deterministic machine that can ask questions to some oracle $A$. Initially $A$ is empty but this is can be changed after ...
Alexey Milovanov's user avatar
10 votes
1 answer
420 views

Is this game EXPSPACE-complete?

Let $M$ be a polynomial-time deterministic machine that can ask questions to some oracle $A$. Initially $A$ is empty but this is can be changed after a game that will be described below. Let $x$ be ...
Alexey Milovanov's user avatar
1 vote
0 answers
52 views

Circuit games in extensive form with imperfect information

Consider $l,m,n,N \in \mathbb{N}$ and circuits $C: \{0,1\}^{l+m} \rightarrow \{0,1\}^l$, $D: \{0,1\}^{l+n} \rightarrow \{0,1\}^l$. Consider the following zero-sum two-layer extensive-form game with ...
Vanessa's user avatar
  • 2,181
2 votes
0 answers
216 views

Two-player zero-sum games in extensive form represented as directed acyclic graphs

The following is a way to represent two-player zero-sum games in extensive form. Consider a directed acyclic graph $G$ where each non-terminal vertex is one of 3 types: player 1 vertex, player 2 ...
Vanessa's user avatar
  • 2,181
16 votes
0 answers
546 views

Quantum Hardness of Finding Nash Equilibria

This question is inspired by the recent, beautiful work On the Cryptographic Hardness of Finding a Nash Equilibrium by Bitansky, Paneth, and Rosen. Their main result is that the existence of ...
Daniel Apon's user avatar
  • 6,051
32 votes
3 answers
2k views

Is this variation of TQBF still PSPACE-complete?

Deciding if a quantified boolean formula such as $\forall x_1 \exists x_2 \forall x_3\cdots \exists x_n \varphi(x_1, x_2,\ldots , x_n),$ always evaluates to true is a classical PSPACE-complete ...
JWM's user avatar
  • 752
7 votes
1 answer
1k views

Why is computing pure Nash equilibria NP-complete?

In this paper, it is claimed that computing pure-strategy Nash equilibria of games in standard normal form is NP-complete. This confuses me, because I do not understand why it is hard to guess the ...
user avatar
3 votes
1 answer
493 views

How do you compute the fixed point of a best-response function efficiently?

I have a polynomial time best-response function that has the same properties as a game-theory game (convexity, compactness, set-valued). I don't know that much topology, but my understanding is that ...
user avatar
4 votes
0 answers
108 views

Games where $\omega(G) < \omega^*(G) < \omega^{ns}(G) < 1$?

A two player game $G = (I,O,V,p)$ is such that, if two non-communicating players Alice and Bob are given questions $(x,y)\in I^2$ drawn from the probability distribution $p$, they are supposed to ...
Henry Yuen's user avatar
  • 3,888
12 votes
2 answers
488 views

How hard is it to count the number of local optima for a problem in PLS?

For a polynomial local search problem, we know that at least one solution (local optimum) must exist. However, many more solutions could exist, how hard is it to count the number of solutions for a ...
Artem Kaznatcheev's user avatar
12 votes
2 answers
475 views

Complexity of finite-state partial information games

Given a deterministic partial-information zero-sum game with only finitely many states, whose possible outcomes are [lose,draw,win] with values [-1,0,+1] respectively, what is the complexity ...
user avatar
19 votes
2 answers
2k views

How hard is Mafia?

Mafia is a popular role-playing game at parties, a detailed description is available at wikipedia http://en.wikipedia.org/wiki/Mafia_%28game%29. Basically, it works as follows: At the beginning, ...
Syzygy's user avatar
  • 291
0 votes
2 answers
726 views

What are the inclusion relationships if any, between the classes Pspace, PLS, PPP, PPA and PPAD

I have been thinking about Pspace in conjunction with searching for a Natural Notion of Stablilty for Complex Dynamical Systems. A natural question in this direction is the Nash equilibrium. ...
Zelah 02's user avatar
  • 1,598
9 votes
1 answer
463 views

What is the Complexity Classification of Portfolio Theory in Financial Economics?

As you will all know, there is ongoing fall out from the Financial Crisis of 2008. I was thinking about how complexity theory fitted into all this, when I realised I did not know the basic complexity ...
Zelah 02's user avatar
  • 1,598
31 votes
1 answer
2k views

Refereed games with uncorrelated semi-private coins

I was (and still am) really interested in the answer to this question, because this is an interesting variation on the complexity of games which hasn't been resolved, so I offered a bounty. I thought ...
34 votes
5 answers
3k views

Evidence that PPAD is hard?

There is often-quoted philosophical justification for believing that P != NP even without proof. Other complexity classes have evidence that they are distinct, because if not, there would be "...
Aaron Roth's user avatar
  • 9,910