Mizel and Sundaresan have
given an integral representation for a class of nonlinear functionals, called additive
functionals, on the Banach spaces Lp, p ≧ 1. In this paper, analogous results
for these additive functionals on the spaces Lp,0 < p < 1, are presented.
The convergence of additive functionals is also investigated whenever three
types of convergence are imposed on the members of Lp: almost everywhere
convergence, convergence in measure, and convergence in the metric d, where
d(x,y) =∫|x−y|pdμ. In all three cases an integral representation for the functional
is obtained, and necessary and sufficient conditions are given for the continuity of the
functional.