* These gates are called “universal” for this reason. Any set of gates that can emulate AND, OR, and NOT is universal. Incredibly, you don’t even need all three of these to make a universal set. An OR gate can be emulated by the proper sequence of ANDs and NOTs: (p ∨ q) is the same as ¬[(¬p) ∧ (¬q)]. Therefore, just NOT and AND are a set of universal gates! In fact, NOT and AND in a single gate—NAND—is a universal gate all by itself, which means a whole bunch of NAND gates is literally all you need to build a complete computer. NOT and OR are universal gates too, making NOR the only other universal single gate operation.