# Normalisations of Existential Rules: Not so Innocuous!

arXiv: https://arxiv.org/abs/2206.03124 · HTML: https://mlsanity.com/paper/2206.03124/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 7 of its 55 references that are in the map.
- First posted on arXiv 7 Jun 2022.

## Builds on (most cited first, 7 of 7)

- [Acyclicity Notions for Existential Rules and Their Application to Query Answering in Ontologies](https://mlsanity.com/paper/1406.4110/) (2014)
- [Sound, Complete and Minimal UCQ-Rewriting for Existential Rules](https://mlsanity.com/paper/1311.3198/) (2013)
- [Anatomy of the chase](https://mlsanity.com/paper/1303.6682/) (2013)
- [Materializing Knowledge Bases via Trigger Graphs](https://mlsanity.com/paper/2102.02753/) (2021)
- [A Single Approach to Decide Chase Termination on Linear Existential Rules](https://mlsanity.com/paper/1810.02132/) (2018)
- [Capturing Homomorphism-Closed Decidable Queries with Existential Rules](https://mlsanity.com/paper/2107.07811/) (2021)
- [All-Instances Restricted Chase Termination](https://mlsanity.com/paper/1901.03897/) (2019)

## Abstract (arXiv)

Existential rules are an expressive knowledge representation language mainly developed to query data. In the literature, they are often supposed to be in some normal form that simplifies technical developments. For instance, a common assumption is that rule heads are atomic, i.e., restricted to a single atom. Such assumptions are considered to be made without loss of generality as long as all sets of rules can be normalised while preserving entailment. However, an important question is whether the properties that ensure the decidability of reasoning are preserved as well. We provide a systematic study of the impact of these procedures on the different chase variants with respect to chase (non-)termination and FO-rewritability. This also leads us to study open problems related to chase termination of independent interest.