We study the interaction of views, queries, and background knowledge in the form of existential rules. The motivating questions concern monotonic determinacy of a query using views w.r.t. rules, which refers to the ability to recover the query answer from the views via a monotone function. We study the decidability of monotonic determinacy, and compare with variations that require the ``recovery function'' to be in a well-known monotone query language, such as conjunctive queries or Datalog. Surprisingly, we find that even in the presence of basic existential rules, the borderline between well-behaved and badly-behaved answerability differs radically from the unconstrained case. In order to understand this boundary, we require new results concerning entailment problems involving views and rules.
@article{arxiv.2407.14907,
title = {Monotone Rewritability and the Analysis of Queries, Views, and Rules},
author = {Michael Benedikt and Stanislav Kikot and Johannes Marti and Piotr Ostropolski-Nalewaja},
journal= {arXiv preprint arXiv:2407.14907},
year = {2024}
}