Published online by Cambridge University Press: 24 October 2008
1. Let ℱ be a family of functions X (t) defined in (0, 2π). The functionals to be considered are of a particular class, namely those which define a correspondence between each function X of ℱ and a number which we denote by F(X). It is convenient to refer to F(X) as the functional.
* Math. Zeit. 5, pp. 186–221 (1919).Google Scholar
* Steinhaus, loc. cit., Hilfsatz 3.
* Loc. cit., Umkehrung des Parallelsatzes 3.
* Loc. cit., Umkehrung des Satzes 3.
† Loc. cit., Satz 3.
* Loc. cit., Parallelsatz 3.
† The case p = 2 is due to Fréchet; loc. cit., Satz 2.