Yes, we do. We have enough for billions, with a b, of years.<p><a href="http:&#x2F;&#x2F;www-formal.stanford.edu&#x2F;jmc&#x2F;progress&#x2F;cohen.html" rel="nofollow">http:&#x2F;&#x2F;www-formal.stanford.edu&#x2F;jmc&#x2F;progress&#x2F;cohen.html</a>