<div data-olk-copy-source="MailCompose"><strong>Renzo Caddeo</strong>, born in Sardinia, is a retired professor of geometry and former director of the Department of Mathematics at the University of Cagliari, where he was the organizer of a Masters course dedicated to the visualization of mathematical objects. Before teaching at Cagliari, he studied in Romania and France. His research interests are in differential geometry, in particular in biharmonic maps between Riemannian manifolds and in the surfaces of certain remarkable three-dimensional spaces. He collaborated with Alfred Gray to realize the extended Italian version of the book Modern Differential Geometry of Curves and Surfaces and with Athanase Papadopoulos on the two-volume work Leonhard Euler, Écrits Sur la Musique and the book Christiaan Huygens, Écrits Sur la Musique et le Son.</div>
<div> </div>
<div><strong>Athanase Papadopoulos</strong> (born 1957) is Directeur de Recherche at the French Centre National de la Recherche Scientifique. His main fields of interest are geometry and topology, the history and philosophy of mathematics, and mathematics and music. He has held visiting positions at the Institute for Advanced Study, Princeton (1984–1985 and 1993–1894), USC (1998–1999), CUNY (Ada Peluso Professor, 2014), Brown University (Distinguished visiting professor, 2017), Tsinghua University, Beijing (2018), and the State University of Saint Petersburg (as the Lamé Chair) (2019), and has had several long visits to the Max-Plank Institute for mathematics (Bonn), the Erwin Schrödinger Institute (Vienna), the Graduate Center of CUNY (New York), the Tata Institute (Bombay), Galatasaray University (Istanbul), the University of Florence (Italy), Fudan University (Shanghai), Gakushuin University (Tokyo) and Presidency University (Calcutta) and Banaras Hindu University. He is the author of more than 220 published articles and 50 monographs and edited books.</div>
