---
title: "The Logic of Occurrence"
authors:
  - "Kenneth D. Forbus"
doi: ""
url: "https://ijcai.org/proceedings/1987/82"
pdf: "https://ijcai.org/proceedings/1987/0082.pdf"
venue: "Proceedings of the Tenth International Joint Conference on Artificial Intelligence"
year: 1987
pages: "409-414"
track: "Knowledge Representation"
keywords:
---

# The Logic of Occurrence

Kenneth D. Forbus

*Proceedings of the Tenth International Joint Conference on Artificial Intelligence*, pages 409-414.

## Abstract

A general problem in qualitative physics is determining the consequences of assumptions about the behavior of a system. If the space of behaviors is represented by an envisionment , many such consequences can be represented by pruning states from the envisionment. This paper provides a: formal logic of oc· currence which justifies the algorithms involved and provides a language for relating specific histories to envisionments. The concepts and axioms are general enough to be applicable to any system of qualitative physics. We further propose the concept of tramverse quantities as a general solution to qualitative versions of Zeno's paradox . The utility of these ideas is illustrated by a rational reconstruction of the pruning algorithms used in FROB, a working AI program.