1. Department of Mathematics, Imperial College London, London SW7 2AZ, United Kingdom
2. Department of Mathematics, Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy http://www-dimat.unipv.it/orrieri
3. Department of Mathematics, Politecnico di Milano, Via E. Bonardi 9, 20133 Milano, Italy https://sites.google.com/view/lucascarpa