He was also denied permission to attend numerous conferences abroad to which he had been invited, and his only contact with Western mathematicians was now only by correspondence.
Siya ay tinanggihan din ng pahintulot na dumalo sa maraming Conferences sa ibang bansa na kung saan siya ay inanyayahan, at sa kanyang makipag-ugnayan lamang sa Western mathematicians ay ngayon lamang sa pamamagitan ng sulat.