Complex sentence: His father was Pavlov Yushkevich a Sorbonne-educated philosopher and a mathematician, active in politics as a Menshevik who was in "ssylka" (deportation) in Siberia, and later in France.
Split into simpler sentences: His father was a Sorbonne-educated philosopher and a mathematician, active in politics. He was a Menshevik who was in "ssylka" (deportation) in Siberia, and later in France.