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He is also a visiting professor at the La Sapienza University and the Opole University, and has been Jean Monnet Visiting Professor of European Interdisciplinary Studies at the Polonia University.
In 1992, he became lecturer in mathematical physics at Maynooth College, The National University of Ireland, subsequently was Royal Society postdoctoral fellow at the University of Innsbruck, Austria, lecturer in Mathematical Sciences Department at the University of Durham, UK, and held a postdoctoral position at La Sapienza University in Rome, Italy.