The author is doomed. <a href="http://en.wikipedia.org/wiki/Metastability_in_electronics" rel="nofollow">http://en.wikipedia.org/wiki/Metastability_in_electronics</a><p>In short if your digital circuit is going to accept arbitrary patterns of inputs then there will be cases that cause it to produce non-stable output for arbitrary periods of time. Curse you, laws of physics.