ELI5: Explain Like I'm 5

Arzelà–Ascoli theorem

Imagine you have a bunch of lines, and you want to figure out if they'll all fit inside of a certain space. To do that, you can use the Arzelà-Ascoli theorem!

This theorem helps us figure out if a bunch of functions (like lines, for example) are "uniformly bounded" and "equicontinuous." That sounds like a lot of big words, so let's break it down even further.

"Uniformly bounded" means that all of the functions in our group stay within a certain range, and they don't get too big or too small.

"Equicontinuous" means that all of the functions in our group change in a smooth and gradual way. They don't make sudden jumps or changes, and they don't have any sharp or sudden corners.

So, the Arzelà-Ascoli theorem says that if we have a bunch of functions that are both uniformly bounded and equicontinuous, then we know for sure that they'll all fit inside of our given space!

It's kind of like fitting a bunch of pieces into a puzzle - if each piece is the right size and shape, and they all fit together smoothly, then we know they'll all fit into the puzzle as a whole.

Overall, the Arzelà-Ascoli theorem is a fancy theorem that helps us figure out if a bunch of functions will all work together nicely.