2-extensions with many points

We give defining equations for function fields over finite fields with many rational places. They are obtained from composita of quadratic extensions of the rational function field

Stable Roommates Problem with Random Preferences

The stable roommates problem with $n$ agents has worst case complexity $O(n^2)$ in time and space. Random instances can be solved faster and with less memory, however. We introduce an algorithm that has average time and space complexity $O(n^\frac{3}{2})$ for random instances. We use this algorithm to simulate large instances of the stable roommates problem and to measure the probabilty $p_n$ that a random instance of size $n$ admits a stable matching. Our data supports the conjecture that $p_n = \Theta(n^{-1/4})$.Comment: 14 pages, 6 figures, 4 algorithms, 1 table; Journal of Statistical Mechanics: Theory and Experiment (2015) P0102

Addendum to "On the pλp^{\lambda} problem"

We prove that the conditions $\lambda<5/19$ and $L\le T^{1/2}$ in Theorems 3 and 4 of our recent paper "On the $p^{\lambda}$ problem" can be omitted.Comment: 7 page

Models as a Tool for Theory Construction: Some Strategies of Preliminary Physics

Theoretical models are an important tool for many aspects of scientific activity. They are used, i.a., to structure data, to apply theories or even to construct new theories. But what exactly is a model? It turns out that there is no proper definition of the term "model" that covers all these aspects. Thus, I restrict myself here to evaluate the function of models in the research process while using "model" in the loose way physicists do. To this end, I distinguish four kinds of models. These are (1) models as special theories, (2) models as a substitute for a theory, (3) toy models and (4) developmental models. I argue that models of the types (3) and (4) are considerably useful in the process of theory construction. This will be demonstrated in an extended case-study from High-Energy Physics.Articl