Moscow State University (1963--1964) Exchange Scholar
Cornell University, Ithaca (1964--1970) Instructor and Assistant Professor
Battelle Institute, Geneva (1970--1974) Research Mathematician
University of Arizona, Tucson (1974--) Associate Professor and Professor
Visiting Positions:
Pontificia Universidade Catolica, Rio de Janeiro (1977--1978) Visiting Professor
Institut des Hautes Etudes Scientifiques, Bures-sur-Yvette (1980--1981) Visiting Professor
Independent University of Moscow (1995--1996) Fulbright Lecturer
National Science Foundation (1996--1997) Program Director
Courant Institute of Mathematical Sciences, New York University (2002--2003) Visiting Member