## Abstract

Databases and knowledge bases could be inconsistent in many ways. The semantical characterization of deductive databases that contain disjunctive or indefinite information has been investigated by Minker and his co-workers (1982, 1987, 1988) and by Henschen and his co-workers (1985, 1988). In both cases, there is one salient feature: the databases are assumed to consist of sentences of the form: A_{1} ∨ ⋯ ∨, A_{n} ← B_{1}&⋯&B_{m}, where each A_{i} and each B_{j} is an atom and n≥ 1. Thus, the database is implicitly assumed to be consistent (it is easy to construct a model for any set of such formulas). What we study here is a method for reasoning about such databases when they are not necessarily consistent. Intuitively, this occurs when the A_{i}'s are restricted not just to atomic formulas, but also to negated atoms. We use the device of annotated atoms introduced by Blair and Subrahmanian (1987, 1988) to achieve this effect. Our semantics is closely related to the existing work of Newton da Costa (1974-1987), whose pioneering work on paraconsistency provides the semantical basis for our formal development.

Original language | English (US) |
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Pages (from-to) | 115-141 |

Number of pages | 27 |

Journal | Theoretical Computer Science |

Volume | 93 |

Issue number | 1 |

DOIs | |

State | Published - Feb 3 1992 |

Externally published | Yes |

## ASJC Scopus subject areas

- Theoretical Computer Science
- General Computer Science