Mathematician Cracks Mystery Beatles Chord

It's the most famous chord in rock 'n' roll, an instantly recognizable twang rolling through the open strings on George Harrison's 12-string Rickenbacker. It evokes a Pavlovian response from music fans as they sing along to the refrain that follows:

   It's been a hard day's night

   And I've been working like a dog

The opening chord to A Hard Day's Night is also famous because for 40 years, no one quite knew exactly what chord Harrison was playing. Musicians, scholars and amateur guitar players alike had all come up with their own theories, but it took a Dalhousie mathematician to figure out the exact formula.

http://www.sciencedaily.com/releases/2008/10/081030201607.htm