Updating intensional predicates in Datalog

摘要

In a Datalog database, updates to intensionally defined relations give rise to problems similar to those related to view updates: it is often difficult them in an unambiguous way by means of updates to base relations. This paper gives two contributions to this problem: (i) the formalization of a declarative, model-theoretic semantics of insertions (and, dually, of deletions), with potential, minimal, and deterministic results; (ii) an operational, proof-theoretic approach that turns out to be equivalent to the declarative one, and so allows effective characterizations of the various properties of results, including determinism.