John Geanakoplos (born March 18, 1955) is an American economist, and the current James Tobin Professor of Economics at Yale University.
His father was the late Professor Emeritus at Yale Deno Geanakoplos (Greek: Κωνσταντίνος Γιαννακόπουλος), a renowned Greek-American historian of Byzantine cultural and religious history, and his mother, Effie Geanakoplos, was an instructor in psychiatry at the Yale Child Study Center.
In 1990-1991 and again in 1999-2000 he directed the economics program at the Santa Fe Institute, where he remains an external professor and chairman of the science steering committee.
Geanakoplos' papers in the 1980s with Paul Klemperer and Jeremy Bulow developed the concept and invented the terminology of strategic complements that is now commonly used in game theory, industrial organization and elsewhere.
[3] Geanakoplos and Polemarchakis (1986),[4] for example, establishes key existence and welfare results in a general incomplete markets model.