The relation between what we see and what we know is never settled.

The PAC learning framework provides a formal way to quantify the learnability of a concept class.

Every mathematical problem has a solution; it's just a matter of finding the right perspective.

Children’s books should be full of warmth, not just lessons.

There's a politics to how materials are used.

我们必须保持警惕，坚决与一切内外敌人作斗争。