Papakyriakopoulos worked in isolation at Athens Polytechnic as research assistant to Professor Nikolaos Kritikos.
But he was enrolled as research student at Athens University, being awarded a PhD in 1943 on the recommendation of Constantin Carathéodory.
The proof, as it turned out, was faulty, but Fox's sponsorship would continue for many years and enabled Papakyriakopoulos to work on his mathematics without concern for financial support.
Papakyriakopoulos sympathized with leftist politics[3] and in 1941 joined the student branch of the National Liberation Front (EAM).
[3] Legend has it that in the United States he lived for 25 years in the same hotel room he used when he first arrived in the country, all of his belongings inside his original luggage.