We examine a simple economic model of network formation where agents benefit from indirect relationships. We show that small-world features—short path lengths between nodes together with highly clustered link structures—necessarily emerge for a wide set of parameters. (JEL: D85, A14, C72)

This report describes a new procedure for measuring higher intellectual processes in the chimpanzee. The fully automatic equipment employed eliminates continuous monitoring by the experimenter and can be modified readily for conducting similar research during space flight.

Understanding the performance and role of each formation in a petroleum play is crucial for the efficient and precise exploration and exploitation of trapped hydrocarbons in a sedimentary basin. The Lorestan basin is one of the most important hydrocarbon basins of Iran, and it includes various oil-prone potential source rocks and reservoir rocks. Previous geochemical studies of the basin were n...

This paper develops a simple model to examine the interaction between partner choice and individual behavior in games of coordination. An important ingredient of our approach is the way we model partner choice: we suppose that a player can establish ties with other players by unilaterally investing in costly pairwise links. In this context, individual efforts to balance the costs and benefits o...

This paper extends the two-way flowmodel of network formation initiated by Bala and Goyal (Econometrica 68(5):1181–1230, 2000) by allowing for partner heterogeneity. In our model if a player i forms a link with player j , then she pays a cost of c j and gets benefits of Vj . Our main result consists of the characterization of strict Nash networks. We find that the introduction of partner hetero...

In this paper we propose that the conventional dichotomy between exemplar-based and prototype-based models of concept learning is helpfully viewed as an instance of what is known in the statistical learning literature as the bias/variance tradeoff. The bias/variance tradeoff can be thought of as a sliding scale that modulates how closely any learning procedure adheres to its training data. At o...

This appendix provides proofs and the entire set of data used in Corbae and Duffy [1]. In particular we show that for the environment laid out in our Corbae and Duffy [1], a marriage network is not only the ex-ante efficient network, but also stable in the sense of being immune to unilateral deviations.

First we develop the theory of reduced instability in order to analyze stability of bifurcating solutions via the Liapunov{Schmidt reduction. Next, this theory is generalized to cover sideband instabilities using a Floquet ansatz. The method is applied to roll patterns in the Swift{Hohenberg equation which serves as a model for pattern formation. We analyze the stability problem of small rolls ...

Vision should provide an explanation of the scene in terms of a causal semantics|what aaects what, and why. An important part of the causal explanation of static scenes is what supports what, or, counterfactu-ally: Why aren't things moving? We use simple naive physical knowledge as the basis of a vertically integrated vision system that explains arbitrarily complex stacked block structures. The...