Bev Littlewood and Lorenzo Strigini, in Scientific American (Nov. 1992), 415 Madison Ave., New York, N.Y. 10017-1111.
Occasional computer failure is a familiar fact of modem life. The usual result is inconvenience, a day's work lost or a rile destroyed. When comput- ers are used in critical applications, however, flaws in the software can spell disaster. During the Per- sian Gulf War, for example, the Patriot missile sys- tem failed to track an Iraqi Scud missile that killed 28 U.S. soldiers. The...