Possibility approach to verifying the rule-base of a linguistic FLC model

For calculating the "degree of firing" value pertaining to a given "IF premise THEN consequence" FLC linguistic rule the "rule input" is used. This degree of firing value expresses the appropriate effect on the consequences of the given rule. This process is a well known, conventional treatment. In this paper it will be shown, that in the same time the premise and the input may also determine the possibility of realizing a rule. This possibility can be used for verifying the rule and for changing the rule-output too. This leads to the optimization of the output. When calculating the possibilistic value the possible functional relation between the rule-premise and rule-consequence is taken into account. For defining the "implication" reflecting the operations between the system's parameters and the roles special "T-norms" are used. It is shown, how the arrangement (sequence) of these norms influences the possibility of the realization of the rule. This sequence has definite effect in this context. For the case of a rule-base consisting of more than one rule it will be shown how the possibility of realization of each rule influences the output and the possibility of the output of the whole rule-system. For this purpose the fundamental theory of possibilistic logic, the methods elaborated for solving fuzzy equations as well as the generalized implication system of fuzzy logic are used.