On Empirical Entropy

We propose a compression-based version of the empirical entropy of a finite string over a finite alphabet. Whereas previously one considers the naked entropy of (possibly higher order) Markov processes, we consider the sum of the description of the random variable involved plus the entropy it induces. We assume only that the distribution involved is computable. To test the new notion we compare the Normalized Information Distance (the similarity metric) with a related measure based on Mutual Information in Shannon's framework. This way the similarities and differences of the last two concepts are exposed.Comment: 14 pages, LaTe

Forgetful maps between Deligne-Mostow ball quotients

We study forgetful maps between Deligne-Mostow moduli spaces of weighted points on P^1, and classify the forgetful maps that extend to a map of orbifolds between the stable completions. The cases where this happens include the Livn\'e fibrations and the Mostow/Toledo maps between complex hyperbolic surfaces. They also include a retraction of a 3-dimensional ball quotient onto one of its 1-dimensional totally geodesic complex submanifolds

Ragweed pollen concentration in the function of meteorological elements in the south-eastern part of Hungary

About 30 % of the Hungarian population has some type of allergy, 65 % of them have pollensensitivity, and at least 60 % of this pollen-sensitivity is caused by ragweed. Number of patients with registered allergic illnesses doubled and number of cases of allergic asthma became four times higher by the late 1990s in Southern Hungary comparing to those in 1960s. The short (or common) ragweed (Ambrosia artemisiifolia = Ambrosia elatior) has the most aggressive pollen of all. Clinical investigations prove that its allergenic pollen is the main reason of the most massive, most serious and most long-lasting pollinosis. The aim of the study is to analyse how ragweed pollen concentration is influenced by meteorological elements in a medium-sized city, Szeged, Southern Hungary. The data basis consists of daily ragweed pollen counts and averages of 11 meteorological parameters for the five-year daily data set, 1997-2001. The southern part of the Great Hungarian Plain (Szeged) is the most polluted region with ragweed pollen, not only in the Carpathian basin itself but in Europe and even worldwide, too. Both starting date (between June 20 and July 13) and finishing date (between October 11-29) of the pollination period vary widely. Duration, average daily count, total count and counts on peak days show definite increasing trends, respectively

Universal generalization and universal inter-item confusability

We argue that confusability between items should be distinguished from generalization between items. Shepard's data concern confusability, but the theories proposed by Shepard and by Tenenbaum & Griffiths concern generalization, indicating a gap between theory and data. We consider the empirical and theoretical work involved in bridging this gap