ELI5: Explain Like I'm 5

Non-abelian class field theory

Alright, let's imagine we are playing a game with numbers. You know how we can add numbers together and multiply them, right? Well, what if we want to play with even cooler numbers called "complex numbers"? They are like the regular numbers you know, but they have a special "i" that represents the square root of -1.

Now, let's say we have a complex number, like 2+3i. We can add and multiply complex numbers just like we do with regular numbers. But what if we want to know more about these complex numbers and find patterns among them?

That's where class field theory comes in. It's like a special rulebook that helps us understand complex numbers better. But here's the cool part: sometimes, the rules for adding and multiplying complex numbers don't work the same way! These special complex numbers are called "non-abelian."

Non-abelian class field theory is all about finding patterns and rules for these non-abelian complex numbers. It helps us understand how they behave when we add and multiply them.

Imagine you have a toy that can transform shapes. In class field theory, we have a similar toy, but it can transform numbers! It takes a regular number and changes it into a complex number with special properties. These special numbers are called "field extensions."

The field extensions have some interesting rules. For example, when we multiply two field extensions together, we get a new field extension. But here's the twist: the order in which we multiply them actually matters!

Let's imagine a scenario where we have three field extensions: A, B, and C. If we multiply A and then B, we get a different answer than if we multiply B and then A. This is called "non-commutativity." In regular numbers, it doesn't matter if we multiply A and then B or B and then A – we get the same result. But with non-abelian complex numbers, the order does matter!

Now, class field theory helps us understand this non-commutativity and find patterns in it. It tells us how we can transform regular numbers into these special non-abelian complex numbers. And it helps us understand how these numbers behave when we add and multiply them.

In conclusion, non-abelian class field theory is like a rulebook that helps us understand and play with non-abelian complex numbers. It helps us find patterns and rules for these special numbers and allows us to explore their unique properties.
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