Funding for this research was provided by:
Ministero dell’Istruzione, dell’Università e della Ricerca
GNSAGA Gruppo Nazionale per le Strutture Algebriche, Geometriche e le loro Applicazioni
Article History
Received: 10 November 2019
Accepted: 22 February 2020
First Online: 16 March 2020
Free to read: This content has been made available to all.