组合数学就像是不用实际计数的计数艺术。
Combinatorics is like the art of counting without actually counting.
The choice is simple: either we protect nature now, or we pay the price later.
You may not be able to alter reality, but you can alter your attitude towards it, and this, paradoxically, alters reality.
愛とは、相手を理解しようとすることだ。
质量从来不是偶然的;它始终是智慧努力的结果。