the excellent algorithm of 3dsMax

Now I am working on dynamic simplification, then I found the optimize and multires algorithm in 3dsMax is very fast, excellent,
If you don’t know what is optimize try do this, start 3dsMax, then create a sphere, then change to modify page, click more button, there is a list, you can find optimize,double click will find the vertices and faces before/after right-bottom of the window
who can tell me, how could they do?

I have no idea how they did it in 3D Max, but I have 2 links for you to check out. The 2 algorithms at the following links could be used dynamically, they’re quite fast.