Andrej Dujella
Andrej Dujella (born 1966 in Pula) is a Croatian a professor of mathematics at the University of Zagreb and a fellow of the Croatian Academy of Sciences and Arts. Life. Born in Pula, a native of Zadar, Dujella got his M.Sc. and Ph.D. in mathematics from the University of Zagreb with a dissertation titled "Generalized Diophantine–Davenport problem". His main area of research is number theory, in particular Diophantine equations, elliptic curves, and applications of number theory in cryptography. Dujella is author of the monograph "Number Theory" (translated from Croatian). Dujella has shown that there doesn't exist  a Diophantine 6-tuple and that there exist at most a finite number of Diophantine 5-tuples. He applied Diophantine tuples to construct elliptic curves with high rank. In 1998, Dujella and Attila Pethő introduced congruence method to obtain lower bound for number of Diophantine 5-tuples.