Affiliations: Dipartimento de Mathematica, Universidade da Madeira,
Campus Universitario da Penteada, 9000-390 Funchal, Madeira, Portugal | ONERA, Department of Information Processing and
Modeling, Toulouse, France | Department of Computer Science, King's College London,
The Strand, London WC2R 2LS, England
Abstract: In the field of information systems the term ``constraint'' is
applied to statements of various kinds. Here we start from the analysis of a
simple example to characterise the different kinds of constraints. It is shown
that constraints may be necessary truths or deontic constraints. Moreover,
deontic constraints are classified into three different types: deontic
constraints about the world, deontic constraints about the representation of
the world (self-completeness), and deontic constraints about the links between
the world and its representation (validity and completeness). We describe a
modal logical framework to define the different types of constraints, to
characterise their violations, and to show how to repair their violations. Two
different general forms of deontic constraints are considered, namely O(�→ψ) and �→O�, and it is shown that, except for deontic
constraints about the world, the latter is more appropriate. Special issues
related to the definition of quantifiers in the context of modal operators are
also considered.
Keywords: Integrity, Information Systems, Modal Logic
