High Quality Content by WIKIPEDIA articles! Valentin Poénaru is a Professor of Mathematics at Université de Paris-Sud. He specializes in low-dimensional topology. Born in Romania, he did his undergraduate studies at the University of Bucharest. In 1962, he was an invited speaker at the International Congress of Mathematicians in Stockholm, Sweden. While at the congress, Poénaru defected, subsequently leaving for France. He defended his Thèse d'État at the University of Paris on March 23, 1963. His dissertation topic was Sur les variétés tridimensionnelles ayant le type d'homotopie de la sphère S3, and was written under the supervision of Charles Ehresmann. After that, he went to the United States, spending four years at Harvard University and Princeton University. In 1967, he returned to France.