---
title: "Combining Qualitative and Quantitative Knowledge to Generate Models of Physical Systems"
authors:
  - "Ulf Söderman"
  - "Jan-Erik Strömberg"
doi: ""
url: "https://ijcai.org/proceedings/1991/170"
pdf: "https://ijcai.org/proceedings/1991/0170.pdf"
venue: "Proceedings of the Twelfth International Joint Conference on Artificial Intelligence"
year: 1991
pages: "1158-1162"
track: "Qualitative Reasoning"
keywords:
---

# Combining Qualitative and Quantitative Knowledge to Generate Models of Physical Systems

Ulf Söderman, Jan-Erik Strömberg

*Proceedings of the Twelfth International Joint Conference on Artificial Intelligence*, pages 1158-1162.

## Abstract

All major approaches to Qualitative Reasoning rely on the existence of a model of the physical system. However, the task of finding a model is usually far from trivial. Within the area of electrical engineering, model building methods have been developed to automatically deduce models from measurements . In this paper we explicitly show how to incorporate qualitative knowledge in order to apply these methods to situations where they do not behave satisfactorily. A program has been developed and applied to a non-trivial example. The qualitative input, in terms of an incomplete bond graph, and the resulting output can be used to form a more complete bond graph. This more informative model is suitable for further reasoning.