On the properties of the Riesz transform of Lebesgue integrable functions
摘要
It is well known that the Riesz transform of a Lebesgue integrable function is generally not Lebesgue integrable. In this paper, using the notions of the A-integral and the Q-integral, introduced by Edward Titchmarsh, we prove analogues of Riesz’s equation and Titchmarsh’s equation for the Riesz transform of a Lebesgue integrable function. In particular, it follows from these equations that if the boundary values of a harmonic function on the upper half-space are Lebesgue integrable, then the boundary values of harmonically conjugate functions are integrable in the sense of the Q-integral and the harmonically conjugate functions are the Poisson A-integrals of their boundary values.