Extremal Fitting Problems for Conjunctive Queries

Autor:	Cate, Balder ten, Dalmau, Victor, Funk, Maurice, Lutz, Carsten
Rok vydání:	2022
Předmět:	Computer Science - Databases
Druh dokumentu:	Working Paper
Popis:	The fitting problem for conjunctive queries (CQs) is the problem to construct a CQ that fits a given set of labeled data examples. When a fitting CQ exists, it is in general not unique. This leads us to proposing natural refinements of the notion of a fitting CQ, such as most-general fitting CQ, most-specific fitting CQ, and unique fitting CQ. We give structural characterizations of these notions in terms of (suitable refinements of) homomorphism dualities, frontiers, and direct products, which enable the construction of the refined fitting CQs when they exist. We also pinpoint the complexity of the associated existence and verification problems, and determine the size of fitting CQs. We study the same problems for UCQs and for the more restricted class of tree CQs. Comment: This is the full version (with appendix) of a paper published in Proceedings of PODS 2023
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/2206.05080 Zobrazit plný text záznamu View this record from Arxiv