Abstract
We introduce the Riesz potential operator for functions defined on a quasi-metric space with a measure and prove sharp Lorentz-norm estimates in the spirit of the results due to O'Neil and Peetre and to Hansson and Brezis-Wainger.
We introduce the Riesz potential operator for functions defined on a quasi-metric space with a measure and prove sharp Lorentz-norm estimates in the spirit of the results due to O'Neil and Peetre and to Hansson and Brezis-Wainger.