7 research outputs found
Widest Paths and Global Propagation in Bounded Value Iteration for Stochastic Games
Solving stochastic games with the reachability objective is a fundamental
problem, especially in quantitative verification and synthesis. For this
purpose, bounded value iteration (BVI) attracts attention as an efficient
iterative method. However, BVI's performance is often impeded by costly end
component (EC) computation that is needed to ensure convergence. Our
contribution is a novel BVI algorithm that conducts, in addition to local
propagation by the Bellman update that is typical of BVI, global propagation of
upper bounds that is not hindered by ECs. To conduct global propagation in a
computationally tractable manner, we construct a weighted graph and solve the
widest path problem in it. Our experiments show the algorithm's performance
advantage over the previous BVI algorithms that rely on EC computation.Comment: v2: an URL to the implementation is adde
Comparison of Algorithms for Simple Stochastic Games (Full Version)
Simple stochastic games are turn-based 2.5-player zero-sum graph games with a
reachability objective. The problem is to compute the winning probability as
well as the optimal strategies of both players. In this paper, we compare the
three known classes of algorithms -- value iteration, strategy iteration and
quadratic programming -- both theoretically and practically. Further, we
suggest several improvements for all algorithms, including the first approach
based on quadratic programming that avoids transforming the stochastic game to
a stopping one. Our extensive experiments show that these improvements can lead
to significant speed-ups. We implemented all algorithms in PRISM-games 3.0,
thereby providing the first implementation of quadratic programming for solving
simple stochastic games
Computer Aided Verification
This open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency