Search Results for author: Đorđe Žikelić

Found 12 papers, 6 papers with code

Solving Long-run Average Reward Robust MDPs via Stochastic Games

no code implementations21 Dec 2023 Krishnendu Chatterjee, Ehsan Kafshdar Goharshady, Mehrdad Karrabi, Petr Novotný, Đorđe Žikelić

First, we derive new computational complexity bounds for solving long-run average reward polytopic RMDPs, showing for the first time that the threshold decision problem for them is in NP coNP and that they admit a randomized algorithm with sub-exponential expected runtime.

Decision Making Decision Making Under Uncertainty

Compositional Policy Learning in Stochastic Control Systems with Formal Guarantees

1 code implementation NeurIPS 2023 Đorđe Žikelić, Mathias Lechner, Abhinav Verma, Krishnendu Chatterjee, Thomas A. Henzinger

We also derive a tighter lower bound compared to previous work on the probability of reach-avoidance implied by a RASM, which is required to find a compositional policy with an acceptable probabilistic threshold for complex tasks with multiple edge policies.

Reachability Poorman Discrete-Bidding Games

no code implementations27 Jul 2023 Guy Avni, Tobias Meggendorfer, Suman Sadhukhan, Josef Tkadlec, Đorđe Žikelić

We consider, for the first time, {\em poorman discrete-bidding} in which the granularity of the bids is restricted and the higher bid is paid to the bank.

Learning Control Policies for Stochastic Systems with Reach-avoid Guarantees

no code implementations11 Oct 2022 Đorđe Žikelić, Mathias Lechner, Thomas A. Henzinger, Krishnendu Chatterjee

We study the problem of learning controllers for discrete-time non-linear stochastic dynamical systems with formal reach-avoid guarantees.

Learning Provably Stabilizing Neural Controllers for Discrete-Time Stochastic Systems

1 code implementation11 Oct 2022 Matin Ansaripour, Krishnendu Chatterjee, Thomas A. Henzinger, Mathias Lechner, Đorđe Žikelić

We show that this procedure can also be adapted to formally verifying that, under a given Lipschitz continuous control policy, the stochastic system stabilizes within some stabilizing region with probability~$1$.

Continuous Control

Learning Stabilizing Policies in Stochastic Control Systems

no code implementations24 May 2022 Đorđe Žikelić, Mathias Lechner, Krishnendu Chatterjee, Thomas A. Henzinger

In this work, we address the problem of learning provably stable neural network policies for stochastic control systems.

Stability Verification in Stochastic Control Systems via Neural Network Supermartingales

no code implementations17 Dec 2021 Mathias Lechner, Đorđe Žikelić, Krishnendu Chatterjee, Thomas A. Henzinger

We consider the problem of formally verifying almost-sure (a. s.) asymptotic stability in discrete-time nonlinear stochastic control systems.

Infinite Time Horizon Safety of Bayesian Neural Networks

1 code implementation NeurIPS 2021 Mathias Lechner, Đorđe Žikelić, Krishnendu Chatterjee, Thomas A. Henzinger

Bayesian neural networks (BNNs) place distributions over the weights of a neural network to model uncertainty in the data and the network's prediction.

reinforcement-learning Reinforcement Learning (RL) +1

Scalable Verification of Quantized Neural Networks (Technical Report)

1 code implementation15 Dec 2020 Thomas A. Henzinger, Mathias Lechner, Đorđe Žikelić

In this paper, we show that verifying the bit-exact implementation of quantized neural networks with bit-vector specifications is PSPACE-hard, even though verifying idealized real-valued networks and satisfiability of bit-vector specifications alone are each in NP.

Computational Efficiency Quantization

Infinite-Duration All-Pay Bidding Games

no code implementations12 May 2020 Guy Avni, Ismaël Jecker, Đorđe Žikelić

In {\em bidding games}, however, the players have budgets, and in each turn, we hold an "auction" (bidding) to determine which player moves the token: both players simultaneously submit bids and the higher bidder moves the token.

Optimizing Expectation with Guarantees in POMDPs (Technical Report)

1 code implementation26 Nov 2016 Krishnendu Chatterjee, Petr Novotný, Guillermo A. Pérez, Jean-François Raskin, Đorđe Žikelić

In this work we go beyond both the "expectation" and "threshold" approaches and consider a "guaranteed payoff optimization (GPO)" problem for POMDPs, where we are given a threshold $t$ and the objective is to find a policy $\sigma$ such that a) each possible outcome of $\sigma$ yields a discounted-sum payoff of at least $t$, and b) the expected discounted-sum payoff of $\sigma$ is optimal (or near-optimal) among all policies satisfying a).

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