ELI5: Explain Like I'm 5

Banach algebra cohomology

Banach algebra cohomology is a way of measuring the holes and bumps in a special type of math called a Banach algebra.

A Banach algebra is like a playground where you can add, subtract, and multiply different objects (called elements) together. But, these objects have to follow certain rules. For example, if you add two elements together, they have to stay within the playground, and if you multiply two elements, the result has to also stay in the playground.

Now, imagine you have a special ball that you can throw around the playground. This ball is called a cocycle, and it can land on different elements within the playground. When the cocycle lands on certain elements, it can tell you if there's a hole or bump in the playground.

But, to make sure you have the most accurate information, you need to use something called a boundary map. The boundary map is like a map that tells the cocycle where it can and cannot land, so it can accurately measure the holes and bumps in the playground.

Overall, Banach algebra cohomology is a way to measure the holes and bumps in a Banach algebra playground using a special ball (cocycle) and a boundary map to guide it.