Coming up trumps

THERE'S not much Persi Diaconis can't do with a deck of cards. As well as the usual tricks, he can perform many of his own devising, and without a hint of boastfulness he declares that when he shuffles a deck- even with only one hand - the cards interleave in perfect sequence. But unlike most magicians, Diaconis's skills go beyond pulling the queen of hearts out of your ear. Thirty-one years ago he turned himself into a mathematician.