Handling hanging nodes

Hi @jorgensd,

Very cool work with the mpc. I appreciate the contribution. It's not really an issue, more an open discussion. I was wondering if dolfinx_mpc could be used to handle hanging nodes? It doesn't seem too far from what is currently implemented.

I plan on using t8code to manage mesh refinement within dolfinx. While I know it's possible to create transitional elements to avoid hanging nodes, and there is currently a pull request to implement this in t8code:

https://elib.dlr.de/187499/1/RemovingHangingFacesFromTreeBasedAMR.pdf

I feel like it adds a lot of complexity to the mesh management strategy as it must be done in post-processing.

I was curious about your thoughts on this and whether or not dolfinx_mpc is a good tool to manage hanging nodes.

Thank you,

Francis Lacombe