---
title: "The Hybrid Phenomena Theory"
authors:
  - "Erling A. Woods"
doi: ""
url: "https://ijcai.org/proceedings/1991/167"
pdf: "https://ijcai.org/proceedings/1991/0167.pdf"
venue: "Proceedings of the Twelfth International Joint Conference on Artificial Intelligence"
year: 1991
pages: "1138-1142"
track: "Qualitative Reasoning"
keywords:
---

# The Hybrid Phenomena Theory

Erling A. Woods

*Proceedings of the Twelfth International Joint Conference on Artificial Intelligence*, pages 1138-1142.

## Abstract

The Hybrid Phenomena Theory (HPT) is a framework for formalizing how dynamic state space models of physical systems are built from first principles. The HPT descends from the Qualitative Process Theory (QPT), [Forbus, 1984], from which it inherits basic concepts like views, phenomena and influences. Howe_ver, the HPT redefines some of these concepts m a more strict manner in order to represent knowledge of physics with the accuracy .needed .to develop full parametric models. Specifically, Influences may specify quantified non-linear functions of several variables. A mechanism denoted subsumption is introduced to ensure consistency in the emerging models when different simplifying assumptions are made . The HPT has been implemented in CLOS.