Riesi is located in Italy (Provincia di Caltanissetta, Sicily) and time zone Europe/Rome.
Places nearby are Sommatino, Ravanusa and Mazzarino.
Palermo is 108 km away, Naples is 393 km away and Rome is 523 km away as the crow flies.
Distances from Riesi to the most important cities in Italy and the world.
37.2807900°
14.0831700°
Ortsteil of Oranienbaum-Wörlitz in Saxony-Anhalt, Germany
https://en.wikipedia.org/wiki/RiesigkTheorem about the dual of a Hilbert space
https://en.wikipedia.org/wiki/Riesz_representation_theorem