On the Complexity of Query Answering under Matching Dependencies for Entity Resolution

TL;DR

This paper investigates the computational complexity of answering queries under Matching Dependencies in entity resolution, identifying both tractable and intractable cases, and establishing a dichotomy for a specific scenario.

Contribution

It advances understanding of the complexity landscape of MD-based query answering, including new intractability results and a dichotomy theorem for a special case.

Findings

Identified intractable cases of resolved query answering.

Established a dichotomy complexity result for a specific MD case.

Extended previous work on tractable classes of MDs.

Abstract

Matching Dependencies (MDs) are a relatively recent proposal for declarative entity resolution. They are rules that specify, given the similarities satisfied by values in a database, what values should be considered duplicates, and have to be matched. On the basis of a chase-like procedure for MD enforcement, we can obtain clean (duplicate-free) instances; actually possibly several of them. The resolved answers to queries are those that are invariant under the resulting class of resolved instances. In previous work we identified some tractable cases (i.e. for certain classes of queries and MDs) of resolved query answering. In this paper we further investigate the complexity of this problem, identifying some intractable cases. For a special case we obtain a dichotomy complexity result.