A better approach to implementing logical operations in circuits is the use of logic gates, which can be built with simple relays. This chapter demonstrates how these logic gates perform logical operations.
实现电路逻辑运算的更好方法是使用逻辑门，可以通过简单的继电器构建。 本章演示了这些逻辑门如何执行逻辑操作。

Toggle the state of the switches with mouse clicks or finger taps.
用鼠标点击或手指轻触切换开关状态。

The kitten selector can be built from logic gates rather than switches.
小猫选择器可以由逻辑门而非开关构建。

Here are two more logic gates that are the inverses of those shown earlier.
这里还有两个逻辑门，它们是前面展示的反元。

In this summary of the four basic logic gates, the switches are now shown as simple boxes at the upper-left. They display 0 if the switch is off and 1 if it's on. You can toggle these switches with either mouse clicks or finger taps. Instead of a lightbulb, the output is shown with a circle labeled 0 or 1.
在这四个基本逻辑门的总结中，开关现在以左上角的简单盒子表示。开关关闭时显示0，开关开着时显示1。 你可以用鼠标点击或手指轻触来切换这些开关。输出不再是灯泡，而是用标记为0或1的圆圈表示。

English mathematician Augustus de Morgan established in the 19th century that the various logical operations are intimately related, as this illustration demonstrates.
英国数学家奥古斯都·德·摩根在19世纪确立了各种逻辑运算密切相关，正如这个例子所示。

• An AND gate with its two inputs inverted is the same as a NOR gate
  两个输入反相的 与门 与 或非门 相同 即：(!A)*(!B) = !(A+B)
• An OR gate with its two inputs inverted is the same as a NAND gate
  两个输入反相的 或门 与 与非门 相同 即：(!A)+(!B) = !(A*B)