ELI5: Explain Like I'm 5

Borel functional calculus

Okay kiddo, let me explain to you what Borel functional calculus is.

Imagine you have a box of crayons with different colors. If I tell you to pick one crayon, you can easily do it because you can see all the colors in the box.

Now, let’s think about a math problem. Suppose you have a number, and you want to find its square. This is easy too because you know the rules of algebra.

But what if I give you a complicated math problem that involves more than just numbers? For example, what if I ask you to find the square of a function instead of a number? This is where Borel functional calculus comes in.

Borel functional calculus is a way of doing math on functions, like you would do on numbers. Instead of using algebra rules, we use a special system that lets us manipulate functions. This system is called the Borel functional calculus.

It works like this: We take a function and break it up into simpler parts, called Borel sets. These sets are like the colors in our crayon box - they help us identify and work with different parts of the function.

Once we have identified the Borel sets, we can use the calculus to do things like take the square, cube, or any other power of a function, just like we would with numbers. This helps us solve complicated math problems that involve functions, and it can be super helpful in lots of different areas of math and science.

So there you have it - Borel functional calculus is a fancy way of doing math on functions using Borel sets, just like picking crayons out of a box. Any questions?