We construct a simple model of monetary exchange where, as in Lagos and Wright (2003), trades take place in both centralized and decentralized markets. However, in constrast to Lagos and Wright, we allow for general preferences and introduce nonconvexities (indivisiblities) and sunspots. In the centralized market, agents can trade statecontingent commodities. We show that nonconvexities and sun...

A new technique is presented for automatic identification of sunspots on the full disk solar images allowing robust detection of sunspots on images obtained from space and ground observations, which may be distorted by weather conditions and instrumental artefacts. The technique applies image cleaning procedures for elimination of limb darkening, intensity noise and noncircular image shape. Sob...

Sunspot penumbrae show a fine structure in continuum intensity that displays considerable dynamics. The magnetic field, in contrast, although also highly structured, has appeared to be relatively static. Here we report the discovery of inward moving magnetic enhancements in the penumbrae of two regular sunspots based on time series of SOHO/MDI magnetograms. Local enhancements of the LOS compone...

For duopoly models, we analyse the concept of coarse correlated equilibrium using simple symmetric devices that the players choose to commit to in equilibrium. In a linear duopoly game, we prove that Nash-centric devices, involving a sunspot structure, are simple symmetric coarse correlated equilibria. Any small unilateral perturbation from such a structure fails to be an equilibrium.

We study a prototypical class of exchange economies with private information and indivisibilities. We establish an equivalence between lottery equilibria and sunspot equilibria and show that the welfare and existence theorems hold. To establish these results, we introduce the concept of the stand-in consumer economy, which is a standard convex, finite consumer, finite good, pure exchange econom...