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Controlling Autonomous Systems Based on Partially Observable Markov Decision Processes
Gyselová, Julie ; Lengál, Ondřej (oponent) ; Češka, Milan (vedoucí práce)
Partially observable Markov decision processes offer a way to model systems with state uncertainty. An agent has limited information (observation) about its current location in the system. A finite-state controller that translates this information to actions that the agent can perform helps the agent interact with the model and achieve its goals. PAYNT is a tool that constructs a design space that contains all possible finite-state controllers of a given size for a POMDP and then tries to find the best FSC among those. In this thesis, I introduce a way to restrict the design space to encode only a subset of the controllers so that PAYNT can find the best controller in a much shorter time. If the used restriction is suitable, the controller quality is not affected. I also implement a method that can make the synthesis method implemented in PAYNT continuously find FSCs of increasing sizes and improving qualities by gradually applying restrictions from a predefined set.
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Using Counter-Examples in Controller Synthesis for POMDPs
Frejlach, Jakub ; Síč, Juraj (oponent) ; Češka, Milan (vedoucí práce)
This thesis examines partially observable Markov decision processes (POMDPs), a prominent stochastic model for decision-making under uncertainty and partial observability. POMDPs have diverse applications, from robot navigation to self-driving vehicles. The undecidable control problem of POMDPs has led to various approaches, including finite-state controllers (FSCs) based on observations and history. Identifying small and verifiable FSCs reduces the synthesis of Markov chains. This thesis focuses on counterexample-guided inductive synthesis (CEGIS) within the PAYNT program, exploring the use of Markov decision processes as counterexamples. A new greedy method for constructing counterexamples is outlined and implemented in PAYNT, showing improvements in some cases compared to the existing method.
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Controlling Autonomous Systems Based on Partially Observable Markov Decision Processes
Gyselová, Julie ; Lengál, Ondřej (oponent) ; Češka, Milan (vedoucí práce)
Partially observable Markov decision processes offer a way to model systems with state uncertainty. An agent has limited information (observation) about its current location in the system. A finite-state controller that translates this information to actions that the agent can perform helps the agent interact with the model and achieve its goals. PAYNT is a tool that constructs a design space that contains all possible finite-state controllers of a given size for a POMDP and then tries to find the best FSC among those. In this thesis, I introduce a way to restrict the design space to encode only a subset of the controllers so that PAYNT can find the best controller in a much shorter time. If the used restriction is suitable, the controller quality is not affected. I also implement a method that can make the synthesis method implemented in PAYNT continuously find FSCs of increasing sizes and improving qualities by gradually applying restrictions from a predefined set.
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