premise: Zafar Mahmud (1923–2016) was a Royal Indian Air Force officer during the second world war, originally stationed in Burma and subsequently stationed in Quetta (in present-day Pakistan) from 1945 to 1947 before the partition of British India. He was sent to England a number of times to train with the Royal Air Force just before and after the war.
hypothesis: Mahmud was born in the year after 1921.
reason: Mahmud was born in 1923. The system was confused by the year.