Kristoffer Arnsfelt Hansen

Exact algorithms for solving stochastic games: extended abstract

Shapleys discounted stochastic games, Everetts recursive games and Gillettes undiscounted stochastic games are classical models of game theory describing two-player zero-sum games of potentially infinite duration. We describe algorithms for exactly solving these games. When the number of positions of the game isbconstant, our algorithms run in polynomial time.

Constant Width Planar Computation Characterizes ACC0

We obtain a characterization of ACC 0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all arcs flow along the same direction of the axis of the cylinder.

Winning Concurrent Reachability Games Requires Doubly-Exponential Patience

We exhibit a deterministic concurrent reachability game PURGATORY

The complexity of solving reachability games using value and strategy iteration

_n

Some Meet-in-the-Middle Circuit Lower Bounds

with

The computational complexity of trembling hand perfection and other equilibrium refinements

n

Approximability and Parameterized Complexity of Minmax Values

non-terminal positions and a binary choice for both players in every position so that any positional strategy for Player 1 achieving the value of the game within given

A New Characterization of ACC^0 and Probabilistic CC^0

\epsilon

Dynamic matchings in convex bipartite graphs

Two standard algorithms for approximately solving two-player zerosum concurrent reachability games are value iteration and strategy iteration. We prove upper and lower bounds of 2mΘ(N) on the worst case number of iterations needed for both of these algorithms to provide non-trivial approximations to the value of a game with N non-terminal positions and m actions for each player in each position.

Lower bounds for circuits with few modular and symmetric gates

We observe that a combination of known top-down and bottom-up lower bound techniques of circuit complexity may yield new circuit lower bounds.