ELI5: Explain Like I'm 5

Gelfand–Fuks cohomology

Gelfand-Fuks cohomology is like a game to understand complicated shapes, called manifolds. Imagine that you are playing with play dough, and you can change its shape in any way you want. If you create a knot or a worm, you can keep bending it until it looks like a circle or a line. This is what mathematicians call a 'manifold.'

Now imagine that you want to understand some special things that happen while you play with the play dough. For example, let's say that one part of the play dough feels rough while the rest is smooth. In Gelfand-Fuks cohomology, we try to understand these types of special things by taking a closer look at the play dough.

So, how do we get a closer look at the play dough? One way is to use a 'flashlight.' But instead of a real flashlight, mathematicians use things called 'cohomology groups.' These groups are like little flashlights that let us see different parts of the play dough.

For example, let's say we are interested in understanding how the play dough changes when we bend it. We can use a cohomology group to help us see these changes, kind of like a flashlight helps us see in the dark. Gelfand-Fuks cohomology uses lots of different cohomology groups, each of which shine their light on different parts of the play dough.

Overall, Gelfand-Fuks cohomology is a way for mathematicians to understand special things that happen when we play with the play dough (manifolds). By shining different flashlights (cohomology groups) on the play dough, we can see how it changes and how we can best mold it into new shapes.