论文标题

统一操作一致的查询答案

Uniform Operational Consistent Query Answering

论文作者

Calautti, Marco, Livshits, Ester, Pieris, Andreas, Schneider, Markus

论文摘要

操作一致的查询答案(CQA)是CQA的最新框架,基于修订的维修定义和一致的答案,这打开了具有明确错误保证的有效近似值的可能性。主要思想是从不一致的数据库开始,直到我们到达一个一致的W.R.T.的数据库开始,以迭代应用操作(例如,事实删除)。给定的一组约束。这使我们可以灵活地选择采用操作的概率,从而使我们能够计算操作修复的概率,从而使需要一个一致答案的概率。为操作分配概率的一种自然方法是将统一的概率分布定位在合理的空间上,例如一组操作维修,导致操作维修的操作序列集以及在维修过程的一定步骤中的一组可用操作。这导致了我们通常称为统一的操作CQA。这项工作的目的是对精确和近似统一的操作CQA进行数据复杂性分析,重点关注功能依赖性(以及其子类)和连接性查询。我们的分析的主要结果(除其他积极和负面结果)是,统一的操作CQA通过确保在场景中存在有效的近似值方案,从而进一步推动了效率界限,这些方案超出了简单的主要键,这似乎是CQA经典方法的极限。

Operational consistent query answering (CQA) is a recent framework for CQA, based on revised definitions of repairs and consistent answers, which opens up the possibility of efficient approximations with explicit error guarantees. The main idea is to iteratively apply operations (e.g., fact deletions), starting from an inconsistent database, until we reach a database that is consistent w.r.t. the given set of constraints. This gives us the flexibility of choosing the probability with which we apply an operation, which in turn allows us to calculate the probability of an operational repair, and thus, the probability with which a consistent answer is entailed. A natural way of assigning probabilities to operations is by targeting the uniform probability distribution over a reasonable space such as the set of operational repairs, the set of sequences of operations that lead to an operational repair, and the set of available operations at a certain step of the repairing process. This leads to what we generally call uniform operational CQA. The goal of this work is to perform a data complexity analysis of both exact and approximate uniform operational CQA, focusing on functional dependencies (and subclasses thereof), and conjunctive queries. The main outcome of our analysis (among other positive and negative results), is that uniform operational CQA pushes the efficiency boundaries further by ensuring the existence of efficient approximation schemes in scenarios that go beyond the simple case of primary keys, which seems to be the limit of the classical approach to CQA.

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