PURR - The Persistent URL Resource Resolver

URLs have a precarious functional lifespan. They resolve the intended target (web page, PDF, audio stream, and so on) only so long as the target is available, otherwise they'll point to a dead end. Unfortunately, because companies fold, management changes, URL hostnames change, pages move, services are upgraded and reorganized, content becomes obsolete, and a host of other reasons, reliable, persistent URLs are the exception to the norm. We implemented PURR to provide persistent URLs to documents in our eprint archives. (See http://library.caltech.edu/digital)

Products of Random Matrices

We derive analytic expressions for infinite products of random 2x2 matrices. The determinant of the target matrix is log-normally distributed, whereas the remainder is a surprisingly complicated function of a parameter characterizing the norm of the matrix and a parameter characterizing its skewness. The distribution may have importance as an uncommitted prior in statistical image analysis.Comment: 9 pages, 1 figur

Lepskii Principle in Supervised Learning

In the setting of supervised learning using reproducing kernel methods, we propose a data-dependent regularization parameter selection rule that is adaptive to the unknown regularity of the target function and is optimal both for the least-square (prediction) error and for the reproducing kernel Hilbert space (reconstruction) norm error. It is based on a modified Lepskii balancing principle using a varying family of norms

Vote-Buying and Reciprocity

While vote-buying is common, little is known about how politicians determine who to target. We argue that vote-buying can be sustained by an internalized norm of reciprocity. Receiving money engenders feelings of obligation. Combining survey data on vote-buying with an experiment-based measure of reciprocity, we show that politicians target reciprocal individuals. Overall, our findings highlight the importance of social preferences in determining political behavior.vote-buying, reciprocity, redistributive politics, voting, social preferences