ELI5: Explain Like I'm 5

Kantor–Koecher–Tits construction

Okay, so imagine you are building a really cool toy out of blocks. You start by putting one block down, and then you add another block next to it. Then you keep adding more blocks until your toy is done!

The Kantor-Koecher-Tits construction works kind of like building a toy out of blocks, but with math. Instead of blocks, we use something called "vector spaces," which are like little boxes that can hold numbers.

First, we start by picking two different vector spaces. We call these vector spaces "K" and "V". Then we take a special kind of math operation called a "Lie bracket" and use it to connect the two vector spaces together.

This Lie bracket operation is like a rule that tells us how we can combine different boxes of numbers together. It's kind of like saying "if you have two boxes of numbers, add them together in a certain way to get a new box of numbers."

Using this Lie bracket operation, we can create a new "Lie algebra" which is like a bigger box that contains both K and V. This Lie algebra is called "K-V" and it has all the possible combinations of the boxes of numbers in K and V.

But we're not done yet! Now we use something called a "Tits-Kantor-Koecher construction" to take this Lie algebra K-V and turn it into something called an "exceptional Jordan algebra." This is a special kind of algebra that has some cool properties that make it useful for other kinds of math problems.

So, in summary, the Kantor-Koecher-Tits construction is a way of connecting two vector spaces using a special math operation called a Lie bracket, and then using another construction to turn it into a special kind of algebra called an exceptional Jordan algebra. Kind of like building a toy out of blocks, but with math!