Professor Christopher Voll was awarded a Feodor Lynen Research Fellowship for Experienced Researchers tenable at the University of Auckland. His host will be Professor Eamonn O’Brien from the Department of Mathematics. Christopher is a professor of mathematics at the University of Bielefeld. He obtained his PhD from Cambridge and held posts at Bonn, Düsseldorf, Oxford, and Southampton before taking up his current position in 2011. His research is broadly in the area of infinite group theory and in particular on aspects of subgroup and representation growth of arithmetic and profinite groups. He is one of the key developers of the relatively new area of research on zeta functions of groups. During his Fellowship, he will focus on long-standing conjectures in group theory. He has previously visited Auckland in 2008 and 2010.