Contour Machining, was Optimizing cutting paths, was Traveling Salesman

There would seem to be quite large differences in approaches to
pocketing or contourng - removing material within the boundries of a
shape.
The contouring method where the toolpath follows the shape, getting
progressively smaller till it reaches the middle seems to be quite
complicated and difficult to implement well on complex shapes, ie.
smoothly and with a minimum of tool retractions.
If anyone knows anything about the algorithms for this then I'd like
to find out some more. I've read a little of the theory on voronoi
diagrams and delaunay triangulation, but it's all pretty much over my
head.

Rab

Has anyone tried XaraX, it's got a very fast, practicaly real time
contouring tool and will import and export .AI ( Adobe Illustrator )
files ?