Linguistic hedges and fuzzy logic

Knowledge representation through linguistic variables characterized by means of fuzzy qualifications and linguistic modifiers that slightly change the qualifications is studied. General classes of modifiers are examined. The first aspect of these modifiers is their ability to be used symbolically, though in a way compatible with fuzzy logic, stressing the fact that possibility theory provides an interface between numerical and symbolic descriptions of evidence. Their second interesting aspect is the fact that they help to give elements of comparison for fuzzy implications, and yield a kind of classification of the available tools. Their third aspect is their capability of allowing gradual knowledge to be used in the context of deduction rules