Ken’ichi Ohshika is a professor of mathematics at Gakushuin University, and a professor emeritus at Osaka University. He received his PhD from the University of Tokyo in 1989, and worked at Tokyo Institute of Technology, University of Tokyo, and Osaka University before joining Gakushuin University. His interests include Kleinian groups, hyperbolic geometry, Teichmüller theory, and 3-manifolds. He has held visiting positions at Institut des Hautes Études Scientifiques (1990-1991, 1999-2000), University of Warwick (1988-89, 1993, 2007), Université de Montréal (1995), Hausdorff Research Institute of Mathematics (2010), Université de Strasbourg (2014, 2019), the Korea Institute of Advanced Science (2009-2015), and Max-Planck Institute of Mathematics (2026).  He is a recipient of the MSJ geometry prize (2012), and the author of more than 70 papers.

Athanase Papadopoulos is Directeur de Recherche at the French Centre National de la Recherche Scientifique. His fields of interest include 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), Presidency University (Calcutta), Banaras Hindu University and the Chebyshev laboratory (Saint Petersburg). He is the author of more than 220 published articles and 50 monographs and edited books.