Generic properties of the core and equilibria of pure exchange economies

We show that for an open dense set of markets with a continuum of traders the number of equilibrium allocations [which by the celebrated theorem of ^{Aumann (Econometrica. 1964, 32. 39–50)} coincide with the core allocations for such markets are finite. This presents a limiting case result that complements similar asymptotic theorems for cores of large economies proved by ^{Bewley (Econometrica 1973, 41, 425–454)}, and ^{Dierker (Journal of Mathematical Economics 1975, 2. 155–169)}. If we require that the measure on the space of agents be one with a finite number of atoms of equal weight, our reasoning recovers the classical results obtained by ^{Debreu (Econometrica. 1970. 38, 387–392)} for economies with a finite number of agents.     

Sequential regularity in smooth production economies

In general equilibrium models where agents trade sequentially in multiple periods, the equilibria that endogenously occur in later periods can be robustly indeterminate if production sets are not everywhere differentiable (as. for example, with linear activities). The present paper proves that if technology is smooth, then equilibria are sequentially regular. That is. the equilibria of the endogenously generated economies occurring in later periods that confirm the unanimous expectations formed by agents in earlier periods are regular (and thus, for example, isolated from other equilibria). The paper also proves and utilizes the standard result that the overall intertemporal equilibria are regular.     

A new necessary condition for Nash implementation

In this paper we formulate a family of conditions called `B_k-monotonicity' that are necessary for Nash implementation, where k is a natural number that indexes a particular condition, and where the condition only becomes more restrictive as k increases. B_k-monotonicity is in general a stricter condition than Maskin monotonicity, and can be used to show that certain social choice correspondences that satisfy Maskin monotonicity cannot be Nash implemented.     

Revealed preference theory on the choice of lotteries

The choice behavior of a decision-maker is said to be consistent with expected utility maximization if there exists a utility function defined on the set of prizes such that the decision-maker chooses lotteries with the highest expected utility. We present a revealed preference characterization of choice behavior that is consistent with expected utility maximization. A necessary and sufficient condition for expected utility maximization is that there does not exist a way to compound lotteries such that the probability distribution over the final prizes generated by the chosen lotteries of each observation is equal to that generated by the rejected lotteries of each observation. Our result is quite general and can be applied to any compact set of prizes and any choice correspondence.     

The elasticity of derived demand, factor substitution, and product demand: Corrections to Hicks' formula and Marshall's Four Rules

The concept of the elasticity of substitution between capital and labor, introduced by John Hicks and Joan Robinson over 75 years ago, has had important implications in labor economics and several areas of economic inquiry. In his The Theory of Wages (1932/1963), Hicks developed a formula that has proven very useful in relating the substitution elasticity to the derived demand for productive factors, the distribution of factor incomes, and Marshall's Four Rules. This short paper shows that the original and subsequent derivations of Hicks' celebrated formula contained a slip (that factor shares are independent of the substitution elasticity and therefore constant), presents a new derivation and a corrected formula, and demonstrates that, with the corrected formula, Marshall's First Rule based on the substitution elasticity is no longer generally valid.     

Unemployment risk, house price risk and the transition into home ownership in the United Kingdom

Using household panel data, this paper examines the impact of income uncertainty, in the form of unemployment risk, on home ownership in the United Kingdom. The existing literature based on cross-sectional studies finds a negative relationship between income uncertainty and home ownership. This paper utilises data on transitions into home ownership and exogenous variation in unemployment risk, avoiding the endogeneity of employment to home ownership status. It also conditions the empirical estimates on a measure of house price volatility utilising a local-level house price index to control house price risk, which might also discourage home ownership. Results show a strong role for unemployment risk in lowering the likelihood of house purchase, but no statistically significant role for house price risk.     

Measuring productivity growth, technical progress, and efficiency changes of CPA firms prior to, and following the Sarbanes–Oxley Act

This paper investigates productivity growth, technical progress, and efficiency change for a group of the 56 largest CPA firms in the US from the period 1996–1999 through the period 2003–2006, where the former preceded, and the latter followed, enactment of the Sarbanes–Oxley Act (SOX). Data envelopment analysis (DEA) is used to calculate Malmquist indices of three measures of interest: productivity growth, technical progress, and efficiency change. Results indicate that CPA firms, on average, experienced a productivity growth of approx. 17% from the pre- to post-SOX period. Consistent with the finding of Banker et al. [Banker RD, Chang H, Natarajan R. Productivity change, technical progress and relative efficiency change in the public accounting industry. Management Science 2005;51:291–304], this productivity gain can be attributed primarily to technical progress rather than a change in relative efficiency. In addition, results indicate that the “Big 4” firms underperformed their non-Big 4 counterparts in both productivity growth and technical progress.     

Implementation in generalized matching problems

We search for (Nash) implementable solutions on a class of one-to-one matching problems which includes both the housing market (Shapley and Scarf, Journal of Mathematical Economics, 1974, 1, 23–28) and marriage problems (Gale and Shapley, American Mathematical Monthly, 1962, 69, 9–15). We show that the core correspondence is implementable. We show, furthermore, that any solution that is Pareto efficient, individually rational, and implementable is a supersolution of the core correspondence. That is, the core correspondence is the minimal solution that is Pareto efficient, individually rational, and implementable. A corollary of independent interest in the context of the housing market is that the core correspondence is the only single-valued solution that is Pareto efficient, individually rational, and implementable.     

The graph of Lindahl correspondence as the unique von Neumann-Morgenstern abstract stable set

In this paper, we consider a continuum economy with a finite number of types of agent, and several private and public goods. The main result of the paper is that the graph of the equal-treatment Lindahl equilibria mapping is the unique abstract stable set with respect to the dominance relation in economies with crowding effects introduced by Vasil'ev et al. in 1995. The external stability of this mapping implies that, for any equal-treatment allocation x in , that is not a Lindahl equilibrium, there exists a subeconomy of such that one of its equal-treatment Lindahl allocations blocks x. This result is a counterpart of the theorem of Mas-Colell for Aumann's atomless market with private goods.     

Hedonic estimation of housing demand elasticity with a markup over marginal costs

We show that recent developments in hedonic pricing theory allow modeling of the equilibrium pricing function as the marginal cost of an additional housing unit plus a markup that varies inversely with the elasticity of demand. Useful information about demand elasticity at a given point on the envelope function can be recovered from the hedonic regression and limited information on marginal costs. In particular, the elasticity of the envelope with respect to any characteristic such as interior area provides information on the elasticity of demand. Relative price elasticities (i.e., elasticities that vary from a base value in a known way with interior area, unit type or neighborhood characteristics) can be computed from the elasticity of the hedonic envelope. Like Yinger (2010), our method is based on a single hedonic equation.We test our method using sales of new high rise condominiums in two districts within Shenzhen, China: Futian and Longgang. The results strongly confirm the main hypothesis of this paper: price elasticity with respect to size is increasing for more complex types of units. Together with estimates of marginal costs of production, these results imply that relative demand elasticity is declining for larger, more complex units.     

Lattice structure of knowledge and agreeing to disagree

This paper is a contribution to the study of the underlying mathematical structure of common-knowledge, which gives the well-known result of Aumann about the impossibility of ‘agreeing to disagree’. We present the Bayesian subjective probability model with player's belief: i.e. a triple (? %plane1D;4AF;, μ), in which i is a player. ? is a lattice in the field of sets of a state space Ω, %plane1D;4AF;, is a correspondence assigning to each state ω a filter %plane1D;4AF;(ω) in ?, and μ is a common-prior. For this model, we impose none of the important restrictions on the information structure in the Aumann-Bacharach model: axiom of knowledge K₁. axiom of transparency K₂ and axiom of wisdom K₃. We can extend both the disagreement theorem of Aumann and the agreement theorem of Geanacoplos and Polemarchakis under the assumption that each ? is an Artinian lattice.     

A topological invariant for competitive markets

This paper summarizes the concepts of global cones and limited arbitrage introduced in Chichilnisky (Economic Theory, 1995, 5, 79–108), and the corresponding results establishing that limited arbitrage is necessary and sufficient for the existence of a competitive equilibrium and for the compactness of Pareto frontier (announced in Chichilnisky (American Economic Review, 1992, 84, 427–434, and Chichilnisky (Bulletin of the American Mathematical Society, 1993, 29, 189–207). Using the same global cones I extend my earlier results to encompass ‘mixed economies’ based on Chichilnisky (CORE Discussion Paper No. 9527, 1995). I introduce a topological invariant for competitive markets which deepens the concept of limited arbitrage. This invariant encodes exact information on the equilibria and on the social diversity of the economy and all its subeconomies, and predicts a failure of effective demand.     

A sufficiency result for constrained economies

This paper presents a general sufficiency result for constrained economies. The result shows that, when an equilibrium allocation satisfies the first order necessary conditions for hybrid efficiency (a new type of constrained efficiency), there exists a marginal cost pricing equilibrium in an associated economy. If this equilibrium is Pareto efficient in the associated economy, then the original equilibrium allocation is hybrid efficient. Hence. the necessary conditions are also sufficient.     

Bargaining and strikes: Towards an evolutionary framework

Conventional models of strikes start with the assumption that the bargainers' uniquely rational beliefs can be worked out in advance. Strikes are then explained as either the result of institutional constraints or of the possibility of irrationality. By contrast the evolutionary approach begins with a recognition that bargaining is naturally indeterminate and that, in the absence of a unique model of rational bargaining, conflict-free agreements between rational trades unions and firms reflect the evolution of one out of many possible conventions. This paper explores the alternative interpretation of strikes afforded by this perspective. In particular, it shows how strikes help shape the dispositions of bargainers (as opposed to just revealing it), how periods of conflict are succeeded by periods of industrial peace (and vice versa), and how the stability of bargaining protocols depends not only on the conventions regulating the relations between unions and firms but also on those between workers and union leaders as well as on technological innovations.