AbstractIt appears far more natural and rewarding to consider “fuzziness” spread over the category of closed sets and semicontinuous set-valued mappings than over a set of points and point-to-point functions considered hitherto; for, none will argue that we actually “see” points (and not sets and singletons) when we study fuzzy sets and systems. This change of attitude merely necessitates an extension of the membership function to set-valued mappings and—with regard to dynamics—a transcription of ordinary differential equations to differential inclusions (i.e., orientor field equations in the case of control problems). However, the proper perspective now requires topology in the spaces under consideration and a shift from Boolean algebra to...