可能近似正确（PAC）学习的概念在计算学习理论中具有基础性意义。
The concept of probably approximately correct (PAC) learning has been foundational in computational learning theory.
历史不仅仅是发生了什么，还包括人们对此的想法和感受。
永远别说永远，因为限制只是幻觉。
People who are really serious about software should make their own hardware.