Numerical modeling in the Arrow-Debreu framework has emerged as a consistent approach for economic analysis. A major disadvantage of the applied general equilibrium (AGE) framework has been the high degree of technical expertise required for formulating and solving these models. This paper...

Introducing default and limited collateral into general equilibrium theory (GE) allows for a theory of endogenous contracts, including endogenous margin requirements on loans. This in turn allows GE to explain liquidity and liquidity crises in equilibrium. A formal definition of liquidity is...

Irving Fisher's Ph.D. thesis, submitted to Yale University in 1891, contains a fully articulated general equilibrium model presented with the broad scope and formal mathematical clarity associated with Walras and his successors. In addition, Fisher presents a remarkable hydraulic apparatus for...

We present a finite system of polynomial inequalities in unobservable variables and market data that observations on market prices, individual incomes and aggregate endowments must satisfy to be consistent with the equilibrium behavior of some pure trade economy. Quantifier elimination is used...

Schumpeter regarded "The Nature of Capital and Income" as one of the three of Fisher's contributions to general theory generally recognized, at the time Schumpeter was writing, as "of first-class importance and originality." The other two were Fisher's "Mathematical Investigations" (1982) and...

We show that there is a broad range of systems of simultaneous equations that arise in economics as descriptions of equilibrium that can be solved in elementary fashion via degree theory. Some of these systems are not susceptible to analysis by standard Brouwer fixed point methods. Two of our...