ELI5: Explain Like I'm 5

Riemannian metric and Lie-bracket in computational anatomy

Hey there kiddo!

Do you know how sometimes we try to measure the distance between two points? Like, if you want to know how far your school is from your house, you can measure it using a ruler or a tape measure.

In math, there are special ways of measuring distance between two points that are called "metrics". One type of metric is a "Riemannian metric", which is named after a mathematician called Bernhard Riemann.

Riemannian metrics are used in something called "computational anatomy", which is a fancy way of saying that we use math to study the human body and how it changes. We might want to measure the distance between two brains or two hearts, for example.

Now, there's also something called a "Lie bracket" that's used in computational anatomy. This might sound like a weird piece of equipment, but it's actually just another type of mathematical tool like a ruler or a tape measure.

A Lie bracket helps us understand how two things are related to each other in space. Let's say you have two boxes, and one is sitting on top of the other. The Lie bracket helps us describe the relationship between the boxes and the space around them.

So, in short:

- A Riemannian metric is a way of measuring distance between two points.
- Computational anatomy uses Riemannian metrics to study the human body and how it changes.
- A Lie bracket is a mathematical tool that helps us understand how two things are related to each other in space.