On the set of regular boundary points
It is well known that for an open set in a Brelot harmonic space, the set \(U_{reg}\) of regular boundary points of U is dense in \(\partial\bar U\); but this is not valid for more general harmonic spaces. In this paper, the author considers a general P-harmonic space X with a countable base and proves the following result: If U is a Keldyš set (i.e., a relatively compact open set such that \(\partial U\backslash U_{reg}\) has vanishing harmonic measure at each point in U), or if X has a base of regular sets and U is any open set, then \(\bar U\backslash\overline{U_{reg}}\) is an absorbent set of \(X\backslash\overline{U_{reg}}\).
scientific article; zbMATH DE number 3869712