Nearly hyperharmonic functions are infima of excessive functions
Abstract
Let be a Hunt process on a locally compact space such that the set of its Borel measurable excessive functions separates points, every function in is the supremum of its continuous minorants in and there are strictly positive continuous functions such that vanishes at infinity. A numerical function on is said to be nearly hyperharmonic, if for all and relatively compact open neighborhoods of , where denotes the exit time of . For every such function , its lower semicontinous regularization is excessive. The main purpose of the paper is to give a short, complete and understandable proof for the statement that every Borel measurable nearly hyperharmonic function on is the infimum of its majorants in . The major novelties of our approach are the following: 1. A quick reduction to the special case, where starting at with the expected number of times the process visits the set of points , where , is finite. 2. The statement that the integral is the infimum of all integrals , and , not only for measures satisfying for some excessive majorant of , but also for all finite measures. At the end, the measurability assumption on is weakened considerably.
Cite
@article{arxiv.1809.08611,
title = {Nearly hyperharmonic functions are infima of excessive functions},
author = {Wolfhard Hansen and Ivan Netuka},
journal= {arXiv preprint arXiv:1809.08611},
year = {2019}
}
Comments
The presentation is improved at various places. In particular, the special case is more restrictive and yields a better intuition, there is a new Lemma 3.5 leading to a simplification in the proof of Theorem 3.4, and the reduction to the special case in Section 4 is shortened. Whereas Sections 5 and 6 are not modified, there is a more general Section 6