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A New Approach to Dynamic Epistemic Logic Planning

Introducing an efficient framework for agent-based planning using possibilities.

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Table of Contents

Dynamic Epistemic Logic (DEL) offers a framework for understanding how agents plan their actions based on what they know and believe. This framework is useful because it allows agents to handle situations where actions can have uncertain outcomes, where they do not have complete information, and where they may have different levels of knowledge about what others know.

In traditional DEL planning, the way information is structured relies on models called Kripke models. However, these models have limitations, especially when it comes to how complex situations are represented and processed. This article introduces a new approach to DEL planning that aims to address some of these efficiency issues while still achieving the same goals as the traditional model.

Overview of DEL Planning

DEL planning focuses on how agents can devise strategies based on their understanding of both the world around them and the knowledge of other agents. The framework helps in planning by modeling different states of knowledge and the effects of actions on those states.

In the DEL framework, epistemic states represent how agents view Possibilities, while event models represent the actions that can change these states. The traditional semantic approach uses Kripke models to define these states and actions.

Problems with Traditional DEL Planning

While the Kripke model-based semantics is expressive, it can lead to complex computational challenges. As the number of agents and possible actions increases, the reasoning required to determine what agents know becomes more difficult. This complexity often makes it hard to use in practical applications, especially in real-time scenarios where quick decisions are necessary.

Research has shown that even simplified versions of DEL can lead to undecidability, meaning that it is not always possible to determine whether a certain plan is achievable. Therefore, many studies have focused on limiting the scope of models to make them more manageable.

Introducing Possibilities in DEL Planning

To overcome the limitations of Kripke models, this article proposes a new approach called "delphic." This method moves away from the traditional semantics and introduces a new concept called possibilities. These possibilities are designed to be more efficient in representing complex epistemic states.

Possibilities are objects that can represent both the actual state of the world and the perceptions of agents about what is possible. By using possibilities, the delphic framework can create a more compact representation of knowledge states.

Benefits of the Delphic Framework

One of the main advantages of using possibilities is that they allow for compact representations of epistemic information. This leads to better performance during planning, as it reduces the amount of data that needs to be processed.

In practical experiments, the delphic framework has shown to be effective in handling various planning scenarios. It can produce results in less time and with fewer resources compared to traditional approaches.

Components of the Delphic Framework

The delphic framework consists of several key components that work together to facilitate effective planning:

  1. Possibilities: These are the central building blocks of the new framework. They enable a more efficient representation of states and knowledge.

  2. Eventualities: In addition to possibilities, the framework introduces eventualities, which represent the actions that can change states. These elements are essential for modeling how agents interact with the world.

  3. Union Update: The framework incorporates a unique update mechanism that efficiently modifies knowledge states in response to actions.

Epistemic States in Delphic Planning

In the delphic framework, an epistemic state is represented through a spectrum of possibilities. Each possibility can be thought of as a potential world that agents consider when making decisions. This contrasts with the traditional models, where each world is treated as a separate entity.

The representation of these states allows for a more straightforward way of tracking changes in knowledge over time. When agents perform actions, the related possibilities can be updated without the need for creating entirely new models, which is common in Kripke-based approaches.

Experimental Evaluation

To test the effectiveness of the delphic framework, an experimental evaluation was conducted using various planning benchmarks. The aim was to compare the performance of the new approach against the traditional Kripke-based semantics.

The evaluation measured key metrics such as time taken to find solutions and the amount of memory used during the planning process. The results showed that the delphic framework consistently outperformed the Kripke-based approach in both time and space efficiency.

Future Directions

The delphic framework opens up new avenues for research and application in the field of epistemic planning. It has the potential to ease the computational burdens faced by traditional models, making it suitable for more complex multi-agent scenarios.

In future work, researchers intend to further enhance the capabilities of the delphic framework, possibly by developing competitive implementations in more advanced programming languages. Additionally, exploring the framework's efficiency in specialized planning scenarios could provide more insights into its practical applications.

Conclusion

The delphic approach to epistemic planning offers a promising alternative to traditional Kripke-based methods. By leveraging possibilities, the framework achieves a more compact representation of knowledge states, leading to improved performance in planning tasks.

The experimental results confirm that the delphic framework not only matches the expressiveness of traditional models but also provides significant advantages in terms of efficiency. As the field continues to evolve, delphic planning could play a crucial role in shaping how agents reason and act in complex, uncertain environments.

Overall, this innovative approach to planning based on a fresh understanding of epistemic states could transform practical applications in fields ranging from artificial intelligence to robotics, paving the way for more effective and responsive agent-based systems.

Original Source

Title: DELPHIC: Practical DEL Planning via Possibilities (Extended Version)

Abstract: Dynamic Epistemic Logic (DEL) provides a framework for epistemic planning that is capable of representing non-deterministic actions, partial observability, higher-order knowledge and both factual and epistemic change. The high expressivity of DEL challenges existing epistemic planners, which typically can handle only restricted fragments of the whole framework. The goal of this work is to push the envelop of practical DEL planning, ultimately aiming for epistemic planners to be able to deal with the full range of features offered by DEL. Towards this goal, we question the traditional semantics of DEL, defined in terms on Kripke models. In particular, we propose an equivalent semantics defined using, as main building block, so-called possibilities: non well-founded objects representing both factual properties of the world, and what agents consider to be possible. We call the resulting framework DELPHIC. We argue that DELPHIC indeed provides a more compact representation of epistemic states. To substantiate this claim, we implement both approaches in ASP and we set up an experimental evaluation to compare DELPHIC with the traditional, Kripke-based approach. The evaluation confirms that DELPHIC outperforms the traditional approach in space and time.

Authors: Alessandro Burigana, Paolo Felli, Marco Montali

Last Update: 2023-07-28 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2307.15451

Source PDF: https://arxiv.org/pdf/2307.15451

Licence: https://creativecommons.org/licenses/by-sa/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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