Rubuta ci gaba don wannan sakin layi - Bayan 1968 Warsaw Pact mamaye Czechoslovakia
, ba a rungume shi da hannu biyu ba. Saboda haka, a shekara ta 1971, ya ƙaura zuwa birnin Ottawa, a ƙasar Kanada, inda ya kafa kuma ya ja-goranci sashen ilmin lissafi na zamani a Jami'ar Carleton, wanda ya shafi ilimin algebra da lissafin yiwuwar abubuwa da kuma ilimin lissafi.