UNIVERSITY OF CALIFORNIA - Feb 14 - In the 1960s, researchers David Gale and Lloyd Shapley were interested in the math behind pairing people up with partners who returned their affections. They developed the deferred acceptance algorithm (also known as the Gale-Shapley algorithm). It establishes a system by which everyone is able to find the person they most prefer from among those who prefer them. In the 1980s, a Harvard economist named Alvin Roth began looking at the National Residency Match Program (NRMP), a system that assigns new doctors to hospitals around the country. In the 1990s, the NRMP was struggling because new doctors and hospitals were often both unsatisfied with its assignments. Roth used Gale and Shapley's work to reshape the NRMP matching algorithm so that it produced matches that were more stable. The Gale-Shapley algorithm also proved useful in helping large urban school districts assign students to schools. The real breakthrough came in 2004. That is when Roth developed the matchmaking principle to help transplant patients find donors. It was a leap that earned Shapley and Roth the Nobel Prize in 2012. The formula is now being employed for other uses, such as helping kids in foster care find adoptive parents.