A method and related system for performing fuzzy procedures in processing devices. The method provides for calculating a degree of activation of a fuzzy proposition represented by input values having a fuzzy set associated to a triangular or trapezoidal membership function. The membership function is defined by a defined range of the input values and by an abscissa of the maximum value assumed by said membership. The method includes storing solve values corresponding to the range of definition and to the abscissa of the maximum value. The degree of activation is calculated as a function of the stored solve values, and storing of solve values includes storing the values measured on the abscissa and further at least one value measured on the ordinate corresponding to the membership function.