Complex sentence: He studied at the Pázmány Péter Catholic University in Budapest, and earned a doctorate there in 1936; his thesis, on higher-dimensional surfaces, was supervised by Lipót Fejér.
Split into simpler sentences: He studied at the Pázmány Péter Catholic University in Budapest, from which he earned a doctorate in 1936. His thesis, on higher-dimensional surfaces, was supervised by Lipót Fejér.