Complex sentence: He made lifelong friends and was involved in a homosexual relationship with Pavel Alexandrov who involved Kolmogorov in 1936 in political persecution of their common teacher, the so-called Luzin affair.
Split into simpler sentences: He made lifelong friends and was involved in a homosexual relationship with Pavel Alexandrov. Both were involved in 1936 in political persecution of their common teacher, the so-called Luzin affair.