Sets, by definition, don't contain duplicates. My argument against Brian Smith's answer also works against this one. The problem is that sets can be infinite in size.
blackjack
<a href="http://c.casalemedia.com/c?s=51816&f=3&id=0" target="_blank"><img src="http://as.casalemedia.com/s?s=51816&u=http://perplexus.info&f=3&id=0&if=0" width="120" height="600" border="0"></a>
flooble's webmaster puzzle
re(3): {P, r, o, o, f}
