Open problems in Tetrahedral mesh generation

As has been the nature of articles listing Open problems in any domain, expect this post to be under construction forever. I want to enter in the field of Tetrahedral mesh generation for which I am gathering the list of open problems. In this pursuit I have found some useful resources some of which I have listed here. But I am expecting list to grow as I become more familiar with this field over time.

Constrained Delaunay tetrahedralization(CDT)

Quality tetrahedral mesh generation

Written on 12 Mar 2015