6,686 research outputs found
On the Impact of Modal Depth in Epistemic Planning (Extended Version)
Epistemic planning is a variant of automated planning in the framework of dynamic epistemic logic. In recent works, the epistemic planning problem has been proved to be undecidable when preconditions of events can be epistemic formulas of arbitrary complexity , and in particular arbitrary modal depth. It is known however that when preconditions are propositional (and there are no postconditions), the problem is between Pspace and Expspace. In this work we bring two new pieces to the picture. First, we prove that the epistemic planning problem with propositional preconditions and without postconditions is in Pspace, and is thus Pspace-complete. Second, we prove that very simple epistemic preconditions are enough to make the epistemic planning problem undecidable: preconditions of modal depth at most two suffice
A Gentle Introduction to Epistemic Planning: The DEL Approach
Epistemic planning can be used for decision making in multi-agent situations
with distributed knowledge and capabilities. Dynamic Epistemic Logic (DEL) has
been shown to provide a very natural and expressive framework for epistemic
planning. In this paper, we aim to give an accessible introduction to DEL-based
epistemic planning. The paper starts with the most classical framework for
planning, STRIPS, and then moves towards epistemic planning in a number of
smaller steps, where each step is motivated by the need to be able to model
more complex planning scenarios.Comment: In Proceedings M4M9 2017, arXiv:1703.0173
Efficient Multi-agent Epistemic Planning: Teaching Planners About Nested Belief
Many AI applications involve the interaction of multiple autonomous agents, requiring those agents to reason about their own beliefs, as well as those of other agents. However, planning involving nested beliefs is known to be computationally challenging. In this work, we address the task of synthesizing plans that necessitate reasoning about the beliefs of other agents. We plan from the perspective of a single agent with the potential for goals and actions that involve nested beliefs, non-homogeneous agents, co-present observations, and the ability for one agent to reason as if it were another. We formally characterize our notion of planning with nested belief, and subsequently demonstrate how to automatically convert such problems into problems that appeal to classical planning technology for solving efficiently. Our approach represents an important step towards applying the well-established field of automated planning to the challenging task of planning involving nested beliefs of multiple agents
Refinement Modal Logic
In this paper we present {\em refinement modal logic}. A refinement is like a
bisimulation, except that from the three relational requirements only `atoms'
and `back' need to be satisfied. Our logic contains a new operator 'all' in
addition to the standard modalities 'box' for each agent. The operator 'all'
acts as a quantifier over the set of all refinements of a given model. As a
variation on a bisimulation quantifier, this refinement operator or refinement
quantifier 'all' can be seen as quantifying over a variable not occurring in
the formula bound by it. The logic combines the simplicity of multi-agent modal
logic with some powers of monadic second-order quantification. We present a
sound and complete axiomatization of multi-agent refinement modal logic. We
also present an extension of the logic to the modal mu-calculus, and an
axiomatization for the single-agent version of this logic. Examples and
applications are also discussed: to software verification and design (the set
of agents can also be seen as a set of actions), and to dynamic epistemic
logic. We further give detailed results on the complexity of satisfiability,
and on succinctness
A Semantic Approach to Decidability in Epistemic Planning (Extended Version)
The use of Dynamic Epistemic Logic (DEL) in multi-agent planning has led to a
widely adopted action formalism that can handle nondeterminism, partial
observability and arbitrary knowledge nesting. As such expressive power comes
at the cost of undecidability, several decidable fragments have been isolated,
mainly based on syntactic restrictions of the action formalism. In this paper,
we pursue a novel semantic approach to achieve decidability. Namely, rather
than imposing syntactical constraints, the semantic approach focuses on the
axioms of the logic for epistemic planning. Specifically, we augment the logic
of knowledge S5 and with an interaction axiom called (knowledge)
commutativity, which controls the ability of agents to unboundedly reason on
the knowledge of other agents. We then provide a threefold contribution. First,
we show that the resulting epistemic planning problem is decidable. In doing
so, we prove that our framework admits a finitary non-fixpoint characterization
of common knowledge, which is of independent interest. Second, we study
different generalizations of the commutativity axiom, with the goal of
obtaining decidability for more expressive fragments of DEL. Finally, we show
that two well-known epistemic planning systems based on action templates, when
interpreted under the setting of knowledge, conform to the commutativity axiom,
hence proving their decidability
Perception and Cognition Are Largely Independent, but Still Affect Each Other in Systematic Ways: Arguments from Evolution and the Consciousness-Attention Dissociation
The main thesis of this paper is that two prevailing theories about cognitive penetration are too extreme, namely, the view that cognitive penetration is pervasive and the view that there is a sharp and fundamental distinction between cognition and perception, which precludes any type of cognitive penetration. These opposite views have clear merits and empirical support. To eliminate this puzzling situation, we present an alternative theoretical approach that incorporates the merits of these views into a broader and more nuanced explanatory framework. A key argument we present in favor of this framework concerns the evolution of intentionality and perceptual capacities. An implication of this argument is that cases of cognitive penetration must have evolved more recently and that this is compatible with the cognitive impenetrability of early perceptual stages of processing information. A theoretical approach that explains why this should be the case is the consciousness and attention dissociation framework. The paper discusses why concepts, particularly issues concerning concept acquisition, play an important role in the interaction between perception and cognition
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