Professor Elie Sanchez University of Marseille, France sanchez@neswup.univ-mrs.fr Title: Truth-Qualification and Fuzzy Relations. Application to Natural Languages and Medical Diagnosis Abstract: Given two fuzzy propositions, how to truth-qualify one of them to induce the other one in a semantical equivalence, is the first basic issue addressed in this paper. In the most general case, the set of solutions of this converse problem is fully characterized. It is introduced two fuzzy subsets of the unit interval (t0 and t1, representing linguistic truth values) that provide best lower and upper approximations when no exact solution can be found: it is so derived best semantic entailments of propositions. In a new approach, the problem is reformulated in terms of fuzzy relation equations, from which results are retrieved and extended. The second part of this paper introduces a truth-possibility index defined from t0 and t1, that will serve to pattern matching purposes, in addition to the usual possibility and necessity measures. A biomedical application, in which medical knowledge is expressed in a rule form, or in a linguistic tableau, illustrates the aggregation of these measures, in a medical diagnosis assistance system, "FuzzIA". About Prof Elie Sanchez: Professor Elie Sanchez, from the University of Marseille, France, is a Doctor in Mathematics (Faculty of Sciences) and a Doctor in Human Biology (Faculty of Medicine). He is the Director of the Neurinfo Research Dept and President of the Neural & Fuzzy Systems Institute, Marseille. He was a former President of the International Fuzzy Systems Association. In 1995 he received the International Grigore MOISIL Gold Medal and Award for "capital contributions to Computer and Information Sciences, namely in the fields of Fuzzy Systems and Artificial Intelligence". He serves on the editorial board of many International journals. After initiating theoretical work on the resolution of fuzzy relation equations he published intensively in fuzzy set theory and in soft computing, in particular with applications to Medicine and Biology (his recent interest lies also DNA Biosoft Computing). Within the Neural & Fuzzy Systems Institute, practical applications (R&D, transfer of technology) of his group include: fuzzy logic based decision support systems ("FuzzIA"), hand-written pattern recognition ("Eureca"), fuzzy logic controlled mobile robots ("Vitaur") and automotive applications (in particular, with Peugeot), vocational guidance systems ("FuzzADe") and Fuzzy Information Retrieval Systems, with optimization of weighted queries by genetic algorithms.