---
title: "Derivation Procedures for Extended Stable Models"
authors:
  - "Luís Moniz Pereira"
  - "Joaquim Nunes Aparício"
  - "José Júlio Alferes"
doi: ""
url: "https://ijcai.org/proceedings/1991/127"
pdf: "https://ijcai.org/proceedings/1991/0127.pdf"
venue: "Proceedings of the Twelfth International Joint Conference on Artificial Intelligence"
year: 1991
pages: "863-868"
track: "Logic Programming"
keywords:
---

# Derivation Procedures for Extended Stable Models

Luís Moniz Pereira, Joaquim Nunes Aparício, José Júlio Alferes

*Proceedings of the Twelfth International Joint Conference on Artificial Intelligence*, pages 863-868.

## Abstract

We present derivation proof procedures for extended stable model semantics. Given program II and goal G, G belongs to the well founded model of II iff there is a W F M-derivation for Gin II. Likewise, given program II and goal G, G belongs to some extended stable model of II iff there is a XSM-derivation for Gin II. Correctness (completeness and soundness) of these procedures is discussed. Example derivations are exhibited, as well as a simple Prolog implementation that directly mirrors the procedures.