Changes by: Yegor N. Bryukhov (ybryukhov at gc.cuny.edu)
Date: 2006-01-29 20:48:19 -0800 (Sun, 29 Jan 2006)
Revision: 8624
Log message:

      unintentionally, I deleted all the new proofs, so I had to restore them, luckily they are trivial.