He has worked for various research institutes, including the Centrum Wiskunde & Informatica (CWI) in the Netherlands, the U.S. National Institute of Standards and Technology (NIST), and the Corporation for National Research Initiatives (CNRI).
Dia sempat bekerja di berbagai institusi riset, termasuk Centrum Wiskunde & Informatica (CWI) di Belanda, National Institute of Standards and Technology (NIST) di Amerika Serikat, dan Corporation for National Research Initiatives (CNRI).