from the piece-of-history dept.
DW100 writes "The Colossus computer that helped the Allies crack messages sent by the Nazis during the Second World War has celebrated its 70th birthday. The machine was a pioneering feat of engineering, able to read 5,000 characters a second to help the team at Bletchley Park crack the German's Lorenz code in rapid time. This helped the Allies gather vital information on the Nazi's plans, and is credited with helping end the war effort early, saving millions of lives."
We warn the reader in advance that the proof presented here depends on a
clever but highly unmotivated trick.
-- Howard Anton, "Elementary Linear Algebra"