Joseph Lehner (October 29, 1912, New York City â August 5, 2013, Haverford, PA) was a mathematician at Michigan State University (1957âÂÂ1963), the University of Maryland (1963âÂÂ1972), and the University of Pittsburgh (1972âÂÂ1980). He worked on automorphic functions and introduced AtkinâÂÂLehner theory.