The frame problem in object-oriented specifications: an exhibition of problems and approaches

We present first a series of examples involving the development of information systems, which suggest a number of desirable features for object-oriented specification techniques, especially those supporting inheritance. Most of these features have difficulties with the so-called frame axioms | assertions which state what values have been left unchanged by some procedure. We then examine the benefits and disadvantages of a variety of proposals for dealing with the frame problem, some of which are based on ideas presented earlier in the literature, while others are novel. The approaches are grouped into two families: one which introduces notational conventions/abbreviation for stating frame axioms, and one which embeds them into the language semantics. Of particular interest may be the introduction of a model-theoretic version of the assumption that things don't change unless they have to, and the possibility of relating this to syntactic techniques for stating such frame axioms in standard logic.Technical report lcsr-TR-20