Francesco Damien "Frank" Calegari is a professor of mathematics at the University of Chicago working in number theory and the Langlands program.

[2] Calegari received his PhD in mathematics from the University of California, Berkeley in 2002 under the supervision of Ken Ribet.

[1][4] Calegari was a von Neumann Fellow of mathematics at the Institute for Advanced Study from 2010 to 2011.

[1][6][7] Calegari works in algebraic number theory, including Langlands reciprocity and torsion classes in the cohomology of arithmetic groups.

[4] In collaboration with Vesselin Dimitrov and Yunqing Tang, Calegari proved[8] the unbounded denominators conjecture of A.O.L.