---
title: "Reasoning about Typicality in Low Complexity DLs: The Logics EL⊥Tmin and DL-Litec Tmin"
authors:
  - "Laura Giordano"
  - "Valentina Gliozzi"
  - "Nicola Olivetti"
  - "Gian Luca Pozzato"
doi: "10.5591/978-1-57735-516-8/IJCAI11-155"
url: "https://ijcai.org/proceedings/2011/155"
pdf: "https://ijcai.org/proceedings/2011/0155.pdf"
venue: "Proceedings of the Twenty-Second International Joint Conference on Artificial Intelligence"
year: 2011
pages: "894-898"
track: ""
keywords:
---

# Reasoning about Typicality in Low Complexity DLs: The Logics EL⊥Tmin and DL-Litec Tmin

Laura Giordano, Valentina Gliozzi, Nicola Olivetti, Gian Luca Pozzato

*Proceedings of the Twenty-Second International Joint Conference on Artificial Intelligence*, pages 894-898. DOI: [10.5591/978-1-57735-516-8/IJCAI11-155](https://doi.org/10.5591/978-1-57735-516-8/IJCAI11-155)

## Abstract

We propose a nonmonotonic extension of low complexity Description Logics EL⊥ and DL-Litecore for reasoning about typicality and defeasible properties. The resulting logics are called EL⊥Tmin and DL-LitecTmin. Concerning DL-LitecTmin, we prove that entailment is in Πp2. With regard to EL⊥Tmin, we first show that entailment remains EXPTIME-hard. Next we consider the known fragment of Left Local EL⊥Tmin and we prove that the complexity of entailment drops to Πp2