potential new topic suggestion: graph center?

[mx-xn]

Hi there, I really like this project you are working on xD! I think these tutorials and the concepts breakdowns would be quite helpful for graph theory new learners.

I see you are still expanding your list, and I'm just wondering do you maybe consider adding a new topic about graph center? I think it's an really interesting and useful concept(as well as the Floyd–Warshall algo comes along w/ it), and I'd love to help contribute if you think that sounds good :)