Complex sentence: Henryk Jabłoński (27 December 1909--27 January 2003) was a Polish Socialist, after 1948 Communist politician, historian and professor at Warsaw University.
Split into simpler sentences: Henryk Jabłoński (27 December 1909--27 January 2003) was a Polish Socialist. After 1948, he became a Communist politician, as well as a historian and professor at Warsaw University.