How can one get the neighbours of a node of a mesh in dolfinx? More specifically, I have the index of a degree of freedom of the mesh and am interested in the indices of the neighbouring degrees of freedom.
Could you be more specific?
Do you here mean a vertex (mesh topology) a node in the mesh (mesh geometry) or a degree of freedom coinciding with a vertex of your mesh?
Each of these questions requires different solutions.
I need to construct a prolongation operator for a MG method for two a P1 function space with a coarse and a refined mesh. So, I mean a degree of freedom coinciding with a vertex. Maybe there is even something like a prolongation operator in dolfinx.