Wald, Abraham (1902–1950)
Born in Cluj, Rumania, Wald came to Vienna in 1927 to study mathematics with Karl Menger, the geometer and son of the economist Carl Menger. Menger introduced Wald to the active mathematical group in Vienna, and secured for him a position as mathematical tutor to the economist Karl Schlesinger. This led to Wald’s producing the first proofs of existence for models of general equilibrium; his analysis was based on Cassel’s restatement of the Walrasian model, as modified by Schlesinger’s treatment of free goods. These works were published in the proceedings of Menger’s mathematical colloquium, and a summary was published in the Zeitschrift für Nationalökonomie in 1936. These papers were remarkable for their time and, with von Neumann’s paper on equilibrium in a model of an expanding economy, are the first significant contributions to the mathematical analysis of general equilibrium models in economics. Wald is the link between the early work by Walras and the later work by Kenneth Arrow, Gerard Debreu and Lionel McKenzie on the existence of competitive equilibria.