1.1928年夏天,我到哥廷根访问了几个星期。按惯例,在夏季的学期有相当多的外国学者在那里集会。他们中的很多人,我是熟悉的,有的甚至是老朋友。我到达的时候,一个年青的荷兰人的一项精彩成果,正引起汇集在那里的数学家们的轰动,这人就是范德瓦尔登——当今的著名学者,而那时还仅仅是一个初学的青年。这项成果是在我到达哥廷根的前几天才获得的,并且几乎遇见我的每一个数学家都对我津津有味地谈起了它。事情的经过是这样的,当地的一位数学家(他的名字我没有记住)在自己的学术工作中接触到下述一个问题:当你无论用什么样的方式将所有自然数的集合分成两部份(例如,奇数与偶数,素数与合数,或用任何另外的方式划分),那么能否断定,在这两部份中至少在有一部分中可以找得到尽可能长的算术 In the summer of 928, I visited Gottingen for a few weeks. As a rule, a large number of foreign scholars gather there during the summer semester. Many of them, I am familiar with, and some are even old friends. When I arrived, a wonderful result of a young Dutchman was causing a stir among the mathematicians who had assembled there. This man was Van der Waalden, a famous scholar today, and at that time was just a beginner. Youth. This result was obtained a few days before I arrived in Göttingen, and every mathematician who met me almost talked about it with relish. The story goes like this. A local mathematician (his name I didn’t remember) touched on one of the following questions in his academic work: when you divide the set of all natural numbers into two in any way Part (for example, odd and even numbers, prime numbers and composite numbers, or divided in any other way), then can we conclude that at least part of the two parts can find the longest possible arithmetic