我不是一个功能主义者。
我没有任何特别的秘诀（用于开发新的证明）……这就是为什么做研究既具有挑战性又具有吸引力的原因。这就像在丛林中迷路，试图利用你能收集到的所有知识来想出一些新的技巧，并且如果运气好的话，你可能会找到出路。
I don't have any particular recipe [for developing new proofs] ... It is the reason why doing research is challenging as well as attractive. It's like being lost in a jungle and trying to use all the knowledge that you can gather to come up with some new tricks, and with some luck you might find a way out.
Critical comments by students should be taken in a friendly spirit， accumulation of material should not stifle the student’s independence.