A problem is in P if it can be solved quickly by a computer, and in NP if a solution can be verified quickly.
On pivoting: "If you're not stubborn， you'll give up on experiments too soon. And if you're not flexible， you'll pound your head against the wall and you won't see a different solution to a problem you're trying to solve."
不平等并非不可避免。它是我们通过所追求的政策做出的选择。
一幅画首先必须关乎它自身，而不是其他东西。