Very interesting read, especially considering I'm struggling with a somewhat related problem: contour offsetting (contour and not polygon because it can include arcs). Eliminating a section from between its neighbours as it shrinks away to nothing would be doable, but the problem is you never know when some other, non-local section of your contour starts interfering with the section you're trying to offset and each-with-each gets rather daunting, fast. For a poor code monkey like me it can all be a bit overwhelming... :)