Kobi Kalmanivich for The EMET Prize for Art, Science and Culture · CC BY-SA 3.0

A mathematician who gave game theory its rigorous account of how rational parties who disagree can still learn to cooperate, or fail to. His work on repeated games showed why long-run relationships sustain trust that a single encounter cannot, insights that reshaped how economists model everything from arms races to business alliances. He shared the 2005 Nobel Memorial Prize in Economic Sciences with Thomas Schelling for advancing conflict and cooperation analysis, and has spent his career at Jerusalem's Hebrew University.