On the existence and uniqueness of integrable solutions of functional equations in Banach space.
Necessary and sufficient conditions are found for the exponential Orlicz norm (generated by with 0 < p ≤ 2) of or to be finite, where is a standard Brownian motion and τ is a stopping time for B. The conditions are in terms of the moments of the stopping time τ. For instance, we find that as soon as for some constant C > 0 as k → ∞ (or equivalently ). In particular, if τ ∼ Exp(λ) or then the last condition is satisfied, and we obtain with some universal constant K > 0....
In one of the earliest monographs that involve the notion of a Schauder basis, Franklin showed that the Gram-Schmidt orthonormalization of a certain Schauder basis for the Banach space of functions continuous on [0,1] is again a Schauder basis for that space. Subsequently, Ciesielski observed that the Gram-Schmidt orthonormalization of any Schauder system is a Schauder basis not only for C[0,1], but also for each of the spaces , 1 ≤ p < ∞. Although perhaps not probable, the latter result would...