Spatial risk measures and applications to max-stable processes

The risk of extreme environmental events is of great importance for both the authorities and the insurance industry. This paper concerns risk measures in a spatial setting, in order to introduce the spatial features of damages stemming from environmental events into the measure of the risk. We develop a new concept of spatial risk measure, based on the spatially aggregated loss over the region of interest, and propose an adapted set of axioms for these spatial risk measures. These axioms quantify the sensitivity of the risk measure with respect to the space and are especially linked to spatial diversification. The proposed model for the cost underlying our definition of spatial risk measure involves applying a damage function to the environmental variable considered. We build and theoretically study concrete examples of spatial risk measures based on the indicator function of max-stable processes exceeding a given threshold. Some interpretations in terms of insurance are provided

Diplomatic devices : the social lives of foreign timepieces in late sixteenth- and early seventeenth-century Japan

The present paper explores the social lives of European timepieces as a particular set of objects in late sixteenth- and early seventeenth-century Japan, when the archipelago first encountered the “Southern Barbarians” from Portugal and Spain. Rather than viewing them solely as instruments of time measurement or as decorative objects, I discuss clocks as actors that moved within networks of exchange primarily between Europe and Japan, but also, significantly, within East Asia and Japan itself. Along their trajectory, these devices assumed shifting and at times contradictory meanings for various actors; this is particularly true in view of the fundamental clash between European and Japanese systems of time-reckoning, which essentially rendered early European-style mechanical clocks ‘timeless’ in Japan, with its equinoctial system of variable hours. For Jesuit missionaries and foreign emissaries who brought these early devices to Japan, they were timekeepers, objects of ecclesiastical use, paragons of European ingenuity, and above all diplomatic tools that granted access and established connections with the Japanese ruling elite. For the Japanese, by contrast, these global objects assumed meaning within their highly developed local gift-culture as desirable novelty items, particularly within the socially volatile environment of the unification of the country under Tokugawa control. My contention is that these microhistories of exchange help us understand why mechanical clocks did not have the same ‘revolutionary’ effect on time-reckoning in Japan as they did in Europe; the social lives of these objects strikingly illustrate the power imbalances in diplomatic negotiations that made Japan impervious to coercion by the European powers

A Graph Theoretical Approach to the Dollar Game Problem

In this thesis we consider a problem in Graph Theory known as the Dollar Game. The Dollar game was first introduced by Matthew Baker of the Georgia Institute of Technology in 2010. It is a game of solitaire, played on a graph, and is a variation of chip firing, or sand-piling games. Baker approached the problem within the context of Algebraic Geometry. It is the goal of this paper to provide an overview of the necessary graph theory to understand the problem presented in this game, as well as background on chip firing games, their history and evolution. Finally we will present a variety of results about the Dollar Game from a graph theoretical standpoint

Quantizing Geometry or Geometrizing the Quantum?

The unsatisfactory status of the search for a consistent and predictive quantization of gravity is taken as motivation to study the question whether geometrical laws could be more fundamental than quantization procedures. In such an approach the quantum mechanical laws should emerge from the geometrical theory. A toy model that incorporates the idea is presented and its necessary formulation in configuration space is emphasized.Comment: Talk given at QTRF 5 conference, 5 pages, typos corrected, reference adde

On the Complexity of Nonrecursive XQuery and Functional Query Languages on Complex Values

This paper studies the complexity of evaluating functional query languages for complex values such as monad algebra and the recursion-free fragment of XQuery. We show that monad algebra with equality restricted to atomic values is complete for the class TA[2^{O(n)}, O(n)] of problems solvable in linear exponential time with a linear number of alternations. The monotone fragment of monad algebra with atomic value equality but without negation is complete for nondeterministic exponential time. For monad algebra with deep equality, we establish TA[2^{O(n)}, O(n)] lower and exponential-space upper bounds. Then we study a fragment of XQuery, Core XQuery, that seems to incorporate all the features of a query language on complex values that are traditionally deemed essential. A close connection between monad algebra on lists and Core XQuery (with ``child'' as the only axis) is exhibited, and it is shown that these languages are expressively equivalent up to representation issues. We show that Core XQuery is just as hard as monad algebra w.r.t. combined complexity, and that it is in TC0 if the query is assumed fixed.Comment: Long version of PODS 2005 pape