ELI5: Explain Like I'm 5

Liouville–Neumann series

Okay kiddo, let me explain the Liouville-Neumann series in a way you can understand. You know how sometimes when you add numbers together, you get a new number? Well, the Liouville-Neumann series is like that, but with an infinite number of terms (which means adding up a lot of numbers).

Here's how it works. You start with a fancy math thing called a partial differential equation (don't worry too much about what that is for now). This equation can be represented as an infinite sum of sines and cosines, kind of like a really long song with lots of different notes.

Now, not all infinite sums are easy to work with. Some of them might not even make sense! But the Liouville-Neumann series is special because it's a convergent series, which means that when you add up all the terms, you get a nice, finite number.

This special series is named after two guys, Liouville and Neumann (who were very smart mathematicians). They figured out that if you take the sum of all the terms in this series, it gives you a solution to the original partial differential equation we started with.

So basically, the Liouville-Neumann series is a way to solve a really complicated math problem using an infinite sum of sines and cosines. It's kind of like putting together a puzzle with a lot of tiny pieces - each term in the series is like a little piece of the solution that, when you put them all together, gives you the complete answer.

Hope that helps, kiddo!