It is often asserted – and it is true! – that Mathematics is an international enterprise. Theorems know no geographic boundaries – what's true in Africa is true in Asia and America as well, and presumably also on Mars or the planets of the Andromeda galaxy.

But there is another important dimension to this internationalism, one closer to home: the free meeting of mathematicians from different places adds a great deal to the pursuit of mathematics. A lot of mathematics is communicated orally, by mathematicians in informal conversation. The research group that remains isolated from the world may be severely limited. So it is that meetings like this one are of great importance in bringing mathematicians together.

Many African mathematicians are already quite familiar with the departments of the US and Europe. But for the magic of international exchange to work fully, the exchange must be really that: it must go both ways. Many US mathematicians have not yet paid scientific visits to Africa; for example, this is my first. I'm truly delighted to have the opportunity this week to get to know so many new African mathematicians, and to deepen my knowledge of our discipline by an interchange with them.

On behalf of the American Mathematical Society, let me express my enthusiasm for encouraging this exchange of cultural and mathematical riches, and my warm appreciation of this great PACOM meeting.

David Eisenbud

President, American Mathematical Society