Fri, 04 Nov 2011 08:00:48 +0100 huffman ex/Tree23.thy: simplify proof of bal_del0
(0) -30000 -10000 -3000 -1000 -300 -100 -30 -10 -1 +1 +10 +30 +100 +300 +1000 +3000 +10000 +30000 tip