Dupe. We covered this about a month back [0]. The link was much better too: Scott Arronson's blog. Also, Knuth/Ben-David's shortened proof [1], announced as

Dupe. We covered this about a month back [0]. The link was much better too: Scott Arronson's blog. Also, Knuth/Ben-David's shortened proof [1], announced as a comment on Arronson's blog. [0] https://news.ycombinator.com/item?id=20338281 https://news.ycombinator.com/item?id=20338281 [1] https://news.ycombinator.com/item?id=20589216 https://news.ycombinator.com/item?id=20589216