Fuzzy Discrete Event Systems: Theory and Its Application to

HIV/AIDS Treatment

Professor Hao Ying

Wayne State University

Department of Electrical and Computer Engineering

To effectively represent deterministic uncertainties and vagueness as well as human subjective observation and judgment encountered in many real-world problems especially those in medicine, we recently originated a theory of fuzzy discrete event systems (DES). We introduced fuzzy states and fuzzy event transition and generalized conventional crisp DES to fuzzy DES. The largely graph-based framework of the crisp DES was unsuitable for the expansion and we thus reformulated it using state vectors and event transition matrices which could be extended to fuzzy vectors and matrices by allowing their elements to take values in [0, 1]. We also extended optimal control of DES to fuzzy DES. The new fuzzy DES theory is consistent with the existing theory, both at conceptual and computation levels, in that the former contains the latter as a special case when the membership grades are either 0 or 1. We further developed the FDES theory so that it possessed self-learning capability.

We have applied the fuzzy DES theory to develop an innovative software system for medical treatment, specifically for the first round of highly active antiretroviral therapy of HIV/AIDS patients. The objective is to build such a system whose treatment regimen choice for any given patient will match expert AIDS physician’s selection to produce the (anticipated) optimal treatment outcome. Preliminary retrospective evaluation of our prototype system using patients treated in our institution’s AIDS Clinical Center demonstrates encouraging results when the system operates in either self-learning mode or non-learning mode. Our approach has the capabilities of generalizing, learning, representing knowledge even in the face of weak consensus of domain experts, and being readily upgradeable to new medical knowledge. These are practically important features to medical applications in general, and HIV/AIDS treatment in particular, as national HIV/AIDS treatment guidelines are modified several times per year.

This research was supported in part by the National Institutes of Health under grant R21 EB001529-01A1, and by Wayne State University under a Research Enhancement Program grant.

Friday, October 5, 2007

3:30 – 4:30 p.m.

Rm. 1500 EECS