Léon Walras
The conceptual framework of equilibrium in a market economy was developed by Léon Walras and further extended by Vilfredo Pareto. It was examined with close attention to generality and rigour by twentieth century mathematical economists including Abraham Wald, Paul Samuelson, Kenneth Arrow and Gérard Debreu. This was part of a wider movement in which Wald also sought to bring greater rigour to decision theory and many mathematicians concentrated on minimising dependence on the axiom of choice.