History of Germany (1945–90) on 13 February 1990. The six foreign ministers met four times in the ensuing months in Bonn (5 May), Berlin (22 June), Paris (17 July), and Moscow (12 September). The Polish Foreign Minister participated in the part of the Paris meeting that dealt with the Polish-German borders. Overcoming Soviet objections to a united Germany's membership in NATO was of key importance. This was accomplished in July when the alliance, led by President George H.W. Bush, issued the London Declaration on a transformed NATO. On 16 July, President Gorbachev and Chancellor Kohl announced the agreement in principle on a united Germany
Mathematics in Nazi Germany would begin with a Nazi salute, a practice that Erich Hecke declined to implement in his classroom. Even before Hitler's rise to power, some mathematicians had already emigrated to the United States for various reasons. John von Neumann had taken a position at the California Institute of Technology in 1929 because he felt anti-semitism in Germany was effecting his career. By 1933, von Neumann had a position at Princeton; though he had maintained ties with Germany until then, he canceled his scheduled lectures in Berlin after Hitler became Chancellor. Other early emigrants from Germany included Theodor Estermann, Hans Freudenthal, Eberhard