If you have trouble reading the article. The article assumes the reader has some knowledge of set notation. Look into it and you will find it easily readable.
>But now, minecraft also has a functor F:(openM)→E, where E is the category of entities, which has as objects just sets of entities and as morphisms the surjective maps
I too learned about categories, functors, and morphisms in my set theory class ..
Don't get me wrong I do know what all of those things are but I didn't learn about them in set theory.
