Conclusions

The Snyder and Tang and the Dobkin and Snyder algorithms are incorrect because they rely on false assumptions about convex polygons. Seemingly, their inventors didn't feel the need to carefully prove such simple assumptions. However, as we have seen, simplicity does not imply truth.

These algorithms are great examples for those of us who don't understand the importance or are too lazy to carefully prove even the most obvious statements. Many people have wondered why we ever needed to prove the Jordan Curve Theorem. It looks obvious. But, what if the theorem was false and Camille Jordan hadn't seen the need prove it, calling it, instead, the ``Jordan Curve Principle''?