vspace{0.2cm}In this paper, we design a data structure for the following problem. Let $pi$ be an $x$-monotone trajectory with $n$ vertices in the plane and $epsilon >0$. We show how to preprocess $pi$ and $epsilon$ into a data structure such that for any horizontal query segment $Q$ in the plane, one can quickly determine the minimal continuous fraction of $pi$ whose Fr{'e}chet and Hausdo...

The existence, uniqueness, and shape of clines in a quantitative trait under selection toward a spatially varying optimum is studied. The focus is on deterministic diploid two-locus n-deme models subject to various migration patterns and selection scenarios. Migration patterns may exhibit isolation by distance, as in the stepping-stone model, or random dispersal, as in the island model. The phe...

We study the stability of a so-called kink profile for the one-dimensional Cahn– Hilliard problem on the real line. We derive optimal bounds on the decay to equilibrium under the assumption that the initial energy is less than three times the energy of a kink and that the initial Ḣ−1 distance to a kink is bounded. Working with the Ḣ−1 distance is natural, since the equation is a gradient flow w...

We examine how interaction choices depend on the interplay of social and physical distance, and show that agents who are more central in the social network, or are located closer to the geographic center of interaction, choose higher levels of interactions in equilibrium. As a result, the level of interactivity in the economy as a whole will rise with the density of links in the social network ...

How do competing firms choose their research strategies in the presence of knowledge spillover? We propose a model of spillover with consumers uniformly distributed in a linear city. By choosing their product locations, firms determine the amount of knowledge spillover each is going to receive. In a three stage game similar to Kamien and Zang (2000) andWeithaus (2005) we show that whether firms...

Many cases of externalities in agricultural production, such as pesticide drift, crosspollination, and offensive odors, are attributable to the incompatibility of neighboring land uses and exhibit distance dependence. We characterize equilibrium spatial patterns of externality-generating and -receiving land uses on a two-dimensional lattice with noncooperative, profit-maximizing producers. In e...

We investigate the equilibrium morphology of a finite volume of liquid placed on two parallel rigid fibers of different radii. As observed for identical radii fibers, the liquid is either in a column morphology or adopts a drop shape depending on the inter-fiber distance. However the cross-sectional area and the critical inter-fiber distance at which the transition occurs are both modified by t...

In this paper we show that ultrametricity can be proved in general starting from two very simple and natural assumptions: that each replica is equivalent to the others (replica equivalence or stochastic stability ) and that all the mutual information about a pair of equilibrium configurations is encoded in their mutual distance or overlap (separability or overlap equivalence).