An approximative inference method for solving ∃∀SO satisfiability problems

  • Authors:
  • Hanne Vlaeminck;Joost Vennekens;Marc Denecker;Maurice Bruynooghe

  • Affiliations:
  • Department of Computer Science, Heverlee, Belgium;Department of Computer Science, Heverlee, Belgium;Department of Computer Science, Heverlee, Belgium;Department of Computer Science, Heverlee, Belgium

  • Venue:
  • Journal of Artificial Intelligence Research
  • Year:
  • 2012

Quantified Score

Hi-index 0.00

Visualization

Abstract

This paper considers the fragment ∃∀SO of second-order logic. Many interesting problems, such as conformant planning, can be naturally expressed as finite domain satisfiability problems of this logic. Such satisfiability problems are computationally hard (Σ2P) and many of these problems are often solved approximately. In this paper, we develop a general approximative method, i.e., a sound but incomplete method, for solving ∃∀SO satisfiability problems. We use a syntactic representation of a constraint propagation method for firstorder logic to transform such an ∃∀SO satisfiability problem to an ∃SO(ID) satisfiability problem (second-order logic, extended with inductive definitions). The finite domain satisfiability problem for the latter language is in NP and can be handled by several existing solvers. Inductive definitions are a powerful knowledge representation tool, and this motivates us to also approximate ∃∀SO(ID) problems. In order to do this, we first show how to perform propagation on such inductive definitions. Next, we use this to approximate ∃∀SO(ID) satisfiability problems. All this provides a general theoretical framework for a number of approximative methods in the literature. Moreover, we also show how we can use this framework for solving practical useful problems, such as conformant planning, in an effective way.