Tran Cao Son

Semantic Web services

The authors propose the markup of Web services in the DAML family of Semantic Web markup languages. This markup enables a wide variety of agent technologies for automated Web service discovery, execution, composition and interoperation. The authors present one such technology for automated Web service composition.

Formalizing sensing actions—a transition function based approach

Abstract In presence of incomplete information about the world we need to distinguish between the state of the world and the state of the agents knowledge about the world. In such a case the agent may need to have at its disposal sensing actions that change its state of knowledge about the world and may need to construct more general plans consisting of sensing actions and conditional statements to achieve its goal. In this paper we first develop a high-level action description language that allows specification of sensing actions and their effects in its domain description and allows queries with conditional plans. We give provably correct translations of domain description in our language to axioms in first-order logic, and relate our formulation to several earlier formulations in the literature. We then analyze the state space of our formulation and develop several sound approximations that have much smaller state spaces. Finally we define regression of knowledge formulas over conditional plans.

Planning with preferences using logic programming

We present a declarative language,

A Constructive semantic characterization of aggregates in answer set programming

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Reasoning with Prioritized Defaults

, for the high-level specification of preferences between possible solutions (or trajectories) of a planning problem. This novel language allows users to elegantly express non-trivial, multi-dimensional preferences and priorities over such preferences. The semantics of

Justifications for logic programs under answer set semantics

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Domain-dependent knowledge in answer set planning

allows the identification of most preferred trajectories for a given goal. We also provide an answer set programming implementation of planning problems with

Logic programs with abstract constraint atoms: The role of computations

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Reasoning and planning with sensing actions, incomplete information, and static causal laws using answer set programming

preferences.

Incremental Information Extraction Using Relational Databases

This technical note describes a monotone and continuous fixpoint operator to compute the answer sets of programs with aggregates. The fixpoint operator relies on the notion of aggregate solution. Under certain conditions, this operator behaves identically to the three-valued immediate consequence operator PaggrP for aggregate programs, independently proposed in Pelov (2004) and Pelov et al. (2004). This operator allows us to closely tie the computational complexity of the answer set checking and answer sets existence problems to the cost of checking a solution of the aggregates in the program. Finally, we relate the semantics described by the operator to other proposals for logic programming with aggregates.