Specifying and Computing Causes for Query Answers in Databases via Database Repairs and Repair Programs

TL;DR

This paper develops a formal framework for identifying causes of query answers in databases at the attribute level using repair programs, extending to causality under integrity constraints.

Contribution

It introduces attribute-level causes and repair semantics, and extends repair programs to handle causality with integrity constraints.

Findings

Attribute-level causes are effectively specified using repair programs.

The approach handles causality under integrity constraints.

Extensions enable reasoning about causes at a finer granularity.

Abstract

A correspondence between database tuples as causes for query answers in databases and tuple-based repairs of inconsistent databases with respect to denial constraints has already been established. In this work, answer-set programs that specify repairs of databases are used as a basis for solving computational and reasoning problems about causes. Here, causes are also introduced at the attribute level by appealing to a both null-based and attribute-based repair semantics. The corresponding repair programs are presented, and they are used as a basis for computation and reasoning about attribute-level causes. They are extended to deal with the case of causality under integrity constraints.