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

The chief beauty about time is that you cannot waste it in advance. The next year, the next day, the next hour are lying ready for you, as perfect, as unspoiled, as if you had never wasted or misapplied a single moment in all your life. You can turn over a new leaf every hour if you choose.

The severity of Russian laws is tempered by the lack of obligation to enforce them.

A writer is someone who pays attention to the world.