Natural limits for harmonic and superharmonic functions
J. R. Diederich · Transactions of the American Mathematical Society · 1976
In this paper it is shown that Fatou’s theorem holds for superharmonic functions in certain Liapunov domains if mean continuous limits are used in place of nontangential limits for which Fatou’s theorem fails. Also, existence of mean continuous limits is established for certain semi-linear elliptic equations in Liapunov domains.