Diversity of Answers to Conjunctive Queries

TL;DR

This paper investigates the problem of selecting a diverse subset of answers to conjunctive queries, aiming to balance solution diversity with computational feasibility, and explores the conditions under which such diverse answer sets can be computed.

Contribution

It introduces the diverse-answering problem for conjunctive queries, analyzing its computational complexity and proposing methods to compute diverse answer sets.

Findings

Diverse-answering problem is computationally challenging.

Conditions for feasible computation of diverse answer sets are identified.

Framework for selecting diverse solutions in query answering is proposed.

Abstract

Enumeration problems aim at outputting, without repetition, the set of solutions to a given problem instance. However, outputting the entire solution set may be prohibitively expensive if it is too big. In this case, outputting a small, sufficiently diverse subset of the solutions would be preferable. This leads to the Diverse-version of the original enumeration problem, where the goal is to achieve a certain level d of diversity by selecting k solutions. In this paper, we look at the Diverse-version of the query answering problem for Conjunctive Queries and extensions thereof. That is, we study the problem if it is possible to achieve a certain level d of diversity by selecting k answers to the given query and, in the positive case, to actually compute such k answers.