Abstract
Similarly as the Kolmogorov probability theory in the first half of the 20th century, the Zadeh fuzzy set theory played a significant role in the second half of the 20th century. In this chapter we present probability theory on intuitionisic fuzzy sets as well as probability spaces on multivalued logic.
Keywords: Uncertainty, Fuzzy set, IF-set, IF-event, MV-algebras, Randomness, Observables.