Search Theory; Current Perspectives

In this article I briefly review recent developments in search theory. Particular attention is given to the framework of directed search. I first illustrate the inefficiency that arises in the equilibrium of standard (undirected) search models. Then I provide a formulation of directed search and show that the resulting equilibrium eliminates the inefficiency. Examples of directed search with price posting and auction are provided both for the market with a finite number of individuals and for a large market. After describing the application of search models in monetary theory, I conclude with a remark on the future research.Search; Efficiency; Unemployment

Adapting Search Theory to Networks

The CSE is interested in the general problem of locating objects in networks. Because of their exposure to search theory, the problem they brought to the workshop was phrased in terms of adapting search theory to networks. Thus, the first step was the introduction of an already existing healthy literature on searching graphs. T. D. Parsons, who was then at Pennsylvania State University, was approached in 1977 by some local spelunkers who asked his aid in optimizing a search for someone lost in a cave in Pennsylvania. Parsons quickly formulated the problem as a search problem in a graph. Subsequent papers led to two divergent problems. One problem dealt with searching under assumptions of fairly extensive information, while the other problem dealt with searching under assumptions of essentially zero information. These two topics are developed in the next two sections

Renormalizability, fundamentality and a final theory: The role of UV-completion in the search for quantum gravity

Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity (QG), where novel empirical data is lacking. One principle widely adopted in the search for QG is UV completion: the idea that a theory should (formally) hold up to all possible high energies. We argue---/contra/ standard scientific practice---that UV-completion is poorly-motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore the reasons for expecting, or desiring, a UV-complete theory, as well as analyse how UV completion is used, and how it should be used, in various specific approaches to QG

On search for the M-Theory Lagrangian

We present a starting point for the search for a Lagrangian density for M-Theory using characteristic classes for flat foliations of bundles.Comment: Latex, 5 pages, no figure

A Search Theory of Rigid Prices

In this paper, I build a model marketplace populated by a finite number of sellers – each producing its own variety of the good – and a continuum of buyers–each searching for a variety he likes. Using the model, I study the response of a seller’s price to privately observed fluctuations in its idiosyncratic production cost. I find that the qualitative properties of this response critically depend on the persistence of the production cost. In particular, if the cost is i.i.d., the seller’s price does not respond at all. If the cost is somewhat persistent, the seller’s price responds slowly and incompletely. If the cost is very persistent, the seller’s price adjusts instantaneously and efficiently to all fluctuations in productivity. I argue that these findings can explain why the monthly frequency of a price change is so much lower for processed than for raw goods.Search Frictions, Asymmetric Information, Rigid Prices, Sticky Prices

Search for Tracker Potentials in Quintessence Theory

We report a significant finding in Quintessence theory that the the scalar fields with tracker potentials have a model-independent scaling behaviour in the expanding universe. So far widely discussed exponential,power law or hyperbolic potentials can simply mimic the tracking behaviour over a limited range of redshift. In the small redshift range where the variation of the tracking parameter $\epsilon$ may be taken to be negligible, the differential equation of generic potentials leads to hyperbolic sine and hyperbolic cosine potentials which may approximate tracker field in the present day universe. We have plotted the variation of tracker potential and the equation of state of the tracker field as function of the redshift $z$ for the model-independent relation derived from tracker field theory; we have also plotted the variation of $V(\Phi)$ in terms of the scalar field $\Phi$ for the chosen hyperbolic cosine function and have compared with the curves obtained by reconstruction of $V(\phi)$ from the real observational data from the supernovae.Comment: 11 pages, 3 figures, late

A Theory of Partially Directed Search

This paper studies a search model of the labor market where firms have private information about the quality of their vacancies, they can costlessly communicate with unemployed workers before the beginning of the application process, but the content of the communication does not constitute a contractual obligation. At the end of the application process, wages are determined as the outcome of an alternating offer bargaining game. The model is used to show that vague non-contractual announcements about compensation - such as those one is likely to find in help-wanted ads - can be correlated with actual wages and can partially direct the search strategy of workers.Random search, directed search, non-cooperative bargaining, Coase conjecture, cheap-talk games

Search theory and applied economic research

In the summer of 2002, the Swiss National Bank (SNB) hosted the “SNB-Fed Cleveland Workshop on Monetary Economics”. Recent years have seen the development of the search-theoretic approach to monetary theory. It has established itself as an important strand of monetary theory in a very short space of time, although it has yet to exert a significant influence on the empirical models that are typically used for monetary policy analysis. This is why the conference organisers, David Altig (Federal Reserve Bank of Cleveland), Aleksander Berentsen (University of Basel) and Thomas Jordan (SNB) decided that the event should focus on linking search theory with applied economic research. This summary article first briefly examines the objectives and challenges of search theory before discussing briefly the conference papers.Search Theory; Monetary Policy; Applied Economic Research