Sergey Dudakov

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To find a minimal real change after an update of a database with integrity constraints (IC) expressed by an extended logic program is proven to be a Σ 2 -complete problem. We define a class of operators expanding the input updates correctly with respect to the IC. The particular monotone expansion operator we describe is incrementally computed in square(More)
Databases with integrity constraints IC are considered For each DB update i e a set of facts to add and of facts to delete the IC implies its correct expansion new facts to add and new facts to delete Simultaneously each expanded update induces a correct simpli cation of the IC In the limit this sequence of expansions and simpli ca tions converges to the(More)
The computational complexity is explored of finding the minimal real change of a database after an update constrained by a logic program. Quite surprisingly, a polynomial time algorithm is discovered which solves this problem for ground IC in partial interpretations. Formulated in a “property” form, even under the premise of fixed database scheme, this(More)
In this paper we investigate computational complexity of the PERF-consistency and PERF-entailment problems for ground normal logic programs. In [3] it is proved that these problems belong to Σ2 and Π P 2 correspondingly. The question of obtaining more accurate results was left as open. We prove that both problems belong to ∆2 . Lower bounds on the(More)
This paper is devoted to the problem of consistency enforcement for logical databases. The enforcement methods we propose compute the minimal real change in a given DB state, which is sufficient to accomplish the input update and preserve the integrity constraints (IC). For IC expressed in the form of a generalized logic program, this problem is proven to(More)
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