Identifying Jewish hate on university campuses is an unsolved challenge, experts have warned a royal commission investigating anti-Semitism.Australia Human Rights Commission president Hugh de Kretser was among several witnesses who teased out the distinction before the inquiry body on Monday.It was the first day of a block of hearings in Melbourne exploring the experience of Jewish students and academics, including efforts by their institutions to combat hate.Mr de Kretser said delineating between legitimate criticism of Israel and anti-Semitism could be "complex"."(There has been) public controversy around where to draw line in terms of criticism of Israel and where it's racism...