Abstract
The Fréchet space fractional power theory developed in Schiavone1 is applied to the retarded potential associated with the three (space)–dimensional wave equation. It is shown that the powers obtained coincide with the corresponding Riesz fractional integral. Standard properties of the fractional integral are deduced from the fractional power theory. An indication of how the techniques developed here may be extended to higher dimensional fractional integrals is given.