This dissertation provides a primary groundwork for implementing circumscriptive (and other) non-monotonic reasoning systems that go beyond previous ones in several respects: to perform forward inference and to maintain a body of valid conclusions, as well as to answer queries, for more expressively complex and larger-scale theories. Our major results build sequentially. 1) We extend the circumscription formalism by generalizing the idea of prioritization (relative precedence) so as to enable, for example, the more adequate representation of source reliability and of default inheritance networks. 2) We show that non-monotonic theories are hierarchically decomposable in a manner analogous to programming languages with side effects. 3) We demonstrate several broad cases of safeties of updating, including updating with new default rules. Enabling conditions include syntactic independence and positivity, as well as relative prioritization. 4) We define a generalized "assumption-based" truth maintenance scheme to support inference and belief revision.
For more detail: see section 1.4 (outline) and section 9.1 (conclusions).
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