---
title: "Processes at Discontinuities"
authors:
  - "Patrick J. Hayes"
  - "Michael Leyton"
doi: ""
url: "https://ijcai.org/proceedings/1989/203"
pdf: "https://ijcai.org/proceedings/1989/0203.pdf"
venue: "Proceedings of the Eleventh International Joint Conference on Artificial Intelligence"
year: 1989
pages: "1267-1271"
track: "Knowledge Representation"
keywords:
---

# Processes at Discontinuities

Patrick J. Hayes, Michael Leyton

*Proceedings of the Eleventh International Joint Conference on Artificial Intelligence*, pages 1267-1271.

## Abstract

Leyton [1988] developed a set of rules by which process-history can be recovered from smooth natural shapes such as outlines of tumors, clouds, or islands. In this paper, we extend this analysis to deal with shapes with first-order discontinuities such as corners, creases and cusps. A simple extension to the notation allows one extra rule to cover most of these phenomena.