I googled around and found this paper to be far more compelling than any of Wikipedia&#x27;s vague explanations:
<a href="http:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1310.6514" rel="nofollow">http:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1310.6514</a>