ELI5: Explain Like I'm 5

Idempotent (ring theory)

Okay kiddo, let's talk about the word "idempotent" in ring theory.

Do you know what a ring is? No, not a ring you wear on your finger. A ring in math is a structure that has two operations: addition and multiplication.

Now, idempotent is a fancy math word that means if you do something twice, it's the same as if you only did it once. For example, if you jump once, it's the same as jumping twice if you only end up at the same height.

In ring theory, idempotent means if you multiply something by itself, you get the same thing back. Let's use the number 2 as an example.

If we multiply 2 by 2, we get 4. But if we multiply 4 by 2 again, we get 8, which is not the same as 2. So 2 is not idempotent.

But what if we look at a different number, like 0? If we multiply 0 by 0, we get 0. And if we multiply 0 by 0 again, we still get 0. So 0 is idempotent.

In some cases, rings can have elements that are idempotent. This means that if you multiply an idempotent element by itself, you get the same element back. This can help simplify some equations and make them easier to solve.

So that's what idempotent means in ring theory, it's when you multiply something by itself and get the same thing back. Pretty cool, huh?