Utilities and distortions: an objective approach to possibilistic coding

We re-take the possibilistic (as opposed to probabilistic) approach to information coding put forward previously. To enhance the possibilistic approach also outside the realm of "subjective" uncertainties, in this paper we adopt an "objective" interpretation of possibilistic source coding based on utility functions and an "objective" interpretation of possibilistic channel coding based on distorsion measures and similarity indices. We stress the relationship between possibilistic coding as based on distorsion between sequences and algebraic coding as based on minimum distances between codewords. We compute the operational (coding-theroretic) entropy for a new class of possibilistic sources.