# A Journey into Ontology Approximation: From Non-Horn to Horn

arXiv: https://arxiv.org/abs/2001.07754 · HTML: https://mlsanity.com/paper/2001.07754/

## Key facts

- Cited by 2 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 21 Jan 2020.

## Built on by (most cited first, 2 of 2)

- [How to Approximate Ontology-Mediated Queries](https://mlsanity.com/paper/2107.05369/) (2021)
- [Modelling Control Arguments via Cooperation Logic in Unforeseen Scenarios](https://mlsanity.com/paper/2210.12114/) (2022)

## Abstract (arXiv)

We study complete approximations of an ontology formulated in a non-Horn description logic (DL) such as ALC in a Horn DL such as~EL. We provide concrete approximation schemes that are necessarily infinite and observe that in the ELU-to-EL case finite approximations tend to exist in practice and are guaranteed to exist when the original ontology is acyclic. In contrast, neither of this is the case for ELU_bot-to-EL_bot and for ALC-to-EL_bot approximations. We also define a notion of approximation tailored towards ontology-mediated querying, connect it to subsumption-based approximations, and identify a case where finite approximations are guaranteed to exist.