ELI5: Explain Like I'm 5

Simplicial abelian group

Ok kiddo, looks like you're ready to learn about simplicial abelian groups!

So, first we need to know what an abelian group is. An abelian group is just a bunch of things (usually numbers) that you can add together and get another thing in the group. The special thing about abelian groups is that the order you add things doesn't matter. For example, if we have the abelian group {1, 2, 3}, we can add them in any order and get the same result:
1 + 2 + 3 = 6
3 + 1 + 2 = 6
2 + 1 + 3 = 6
and so on.

Now, a simplicial abelian group is just like an abelian group, but it has more structure. Imagine a shape, like a triangle or square. A simplicial abelian group is a way of assigning an abelian group to each little piece of the shape. So for every point, we have an abelian group. For every line connecting two points, we have a way to add those two groups together to get another group. For every triangle connecting three points, we have a way to add those three groups together to get another group. And so on, for every piece of the shape.

The cool thing about simplicial abelian groups is that they let us study the shape in a really detailed way. We can look at how the groups change as we move around the shape, or as we change the shape itself. And because we're working with abelian groups, we know that we can add things in any order we want, which makes things a lot easier.

Overall, simplicial abelian groups are just a way of assigning mathematical objects (the abelian groups) to each little part of a shape, so we can study the shape in a detailed and structured way. It's kind of like playing with Legos - we can build bigger and more complex things by putting together lots of little pieces, and we can see how everything fits together. Cool, huh?
Related topics others have asked about: