Preference Queries over Taxonomic Domains

TL;DR

This paper addresses the challenge of retrieving the most suitable results based on multiple, potentially conflicting preferences expressed over taxonomic domains, proposing operators to enforce transitivity and specificity, and evaluating their effectiveness.

Contribution

It introduces two preference rewriting operators to ensure transitivity and specificity, and develops a heuristic-based technique for selecting optimal results in taxonomic preference queries.

Findings

Operators effectively enforce transitivity and specificity.

The heuristic approach improves result relevance.

Experimental results confirm practical feasibility.

Abstract

When composing multiple preferences characterizing the most suitable results for a user, several issues may arise. Indeed, preferences can be partially contradictory, suffer from a mismatch with the level of detail of the actual data, and even lack natural properties such as transitivity. In this paper we formally investigate the problem of retrieving the best results complying with multiple preferences expressed in a logic-based language. Data are stored in relational tables with taxonomic domains, which allow the specification of preferences also over values that are more generic than those in the database. In this framework, we introduce two operators that rewrite preferences for enforcing the important properties of transitivity, which guarantees soundness of the result, and specificity, which solves all conflicts among preferences. Although, as we show, these two properties cannot be fully achieved together, we use our operators to identify the only two alternatives that ensure transitivity and minimize the residual conflicts. Building on this finding, we devise a technique, based on an original heuristics, for selecting the best results according to the two possible alternatives. We finally show, with a number of experiments over both synthetic and real-world datasets, the effectiveness and practical feasibility of the overall approach.