...thatthebasisfortheapplicabilityoftheresultsofthemathematicaltheoryofprobabilitytoreal'randomphenomena'mustdependonsomeformofthefrequencyconceptofprobability,theunavoidablenatureofwhichhasbeenestablishedbyvonMisesinaspiritedmanner.
What's a sentence that uses these characters?
... that the basis for the applicability of the results of the mathematical theory of probability to real 'random phenomena' must depend on some form of the frequency concept of probability, the unavoidable nature of which has been established by von Mises in a spirited manner.