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2012Sveriges Riksbank Prize · Search, experiments, and climate

Alvin Roth and Lloyd Shapley

Citation: For the theory of stable allocations and the practice of market design.

The key idea

Shapley: stable matching in two-sided markets (deferred-acceptance algorithm). Roth: take the theory to the field — kidney exchange, school choice, medical residency.

The explanation

Shapley-Gale (1962) showed that the deferred-acceptance algorithm always produces stable matchings (no pair would rather match outside the assignment). Roth implemented this in real markets: kidney-exchange clearinghouses, school-choice systems in Boston and NYC, the National Resident Matching Program for medical residents.

Why Africa should care

Mechanism-design for African public-service allocation is wide open: school-placement systems in South Africa, Kenya's KCSE-to-university selection, public housing waiting lists, kidney transplant matching. Roth-Shapley algorithms are immediately applicable wherever you have two-sided matching with preferences and need stability and strategy-proofness.

How to use it

Whenever you allocate scarce slots (school places, internship matches, transplant priority), use a deferred-acceptance algorithm. It is strategy-proof on one side and stable in equilibrium.

Canonical works

  • David Gale and Lloyd S. Shapley (1962) "College Admissions and the Stability of Marriage" American Mathematical Monthly
  • Alvin E. Roth and Marilda A. O. Sotomayor (1990) "Two-Sided Matching: A Study in Game-Theoretic Modeling and Analysis" Cambridge University Press
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