ELI5: Explain Like I'm 5

Hahn decomposition theorem

Okay kiddo, imagine you have a bag of toys. Now, some of those toys might be your favorites, like your teddy bear or your toy car. Other toys might not be as special to you, but you still like playing with them. And then there might be some toys that you really don't care about at all - maybe they're broken or just boring.

The Hahn Decomposition Theorem is kind of like separating your toys into different bags based on how much you like them. It's a math concept that helps us split up a set of numbers into two groups - one group that we really like, and one group that we don't care as much about.

Let's say we have a bunch of numbers (1, 2, 3, 4, 5, 6, 7, 8, 9, 10). We want to split them up into two groups - one group that has all the odd numbers, and one group that has all the even numbers.

The Hahn Decomposition Theorem says that we can do this, and there's only one way to do it. We can't put any odd numbers in the even group, and we can't put any even numbers in the odd group.

So we could put all the odd numbers (1, 3, 5, 7, 9) in one bag, and all the even numbers (2, 4, 6, 8, 10) in another bag. That way, we've separated the numbers based on whether they're odd or even, and we haven't mixed them up.

The Hahn Decomposition Theorem helps us do this kind of separation for more complicated sets of numbers, too. It's a really useful tool for mathematicians when they're working with tricky problems, because it helps them organize the numbers in a way that makes sense.