Recently, U.S. politicians have come up with costly ideas to improve border security. Some want to hire more Border Patrol agents. Others push for a guest-worker program. And one, Rep. Duncan Hunter, R-Calif., wants to build a 2,000-mile-long wall. Stefan Schmidt, a researcher at New Mexico State University's Physical Science Laboratory, came up with a pretty cheap alternative -- mathematics. "We have ways of modeling to see how we can make the border more secure without paying too much money," Schmidt said. Border Patrol spokesman Doug Mosier said his agency is constantly gathering intelligence to try to predict where smugglers...