Complex sentence: He left Cabinet with Mulroney's retirement in 1993 and was not a candidate in the 1993 Canadian election preferring to leave politics and return to academia becoming vice-dean in the Faculty of Arts and Science at Concordia.
Split into simpler sentences: He left Cabinet with Mulroney's retirement in 1993, and was not a candidate in the 1993 election. He became vice-dean in the Faculty of Arts and Science at Concordia.