An Australian mathematician has solved a problem that has confronted generations of youngsters and stumped a few adults -- lacing shoes. Most people use the criss-cross or the straight lace technique but Burkard Polster, of the Monash University in Victoria, Australia, has shown that although they are the strongest, neither is the most efficient method. "We demonstrate mathematically that the shortest lacing is neither of these, but instead is a rarely used and unexpected type of lacing known as bow-tie lacing," Polster said in research reported in the science journal Nature. The bow-tie technique, in which the laces go across...