Fibration Categories are Fibrant Relative Categories

A relative category is a category with a chosen class of weak equivalences. Barwick and Kan produced a model structure on the category of all relative categories, which is Quillen equivalent to the Joyal model structure on simplicial sets and the Rezk model structure on simplicial spaces. We will prove that the underlying relative category of a model category or even a fibration category is fibrant in the Barwick--Kan model structure.Comment: 21 pages; comments welcom

World Views, Political Attitudes and Risk Perception

Dr. Sjöberg questions the Cultural Theory approach to evaluating variance in risk perception. He also presents the results of a survey using elements of that and other scales to help explain individual differences in risk perception

Additive decompositions for rings of modular forms

We study rings of integral modular forms for congruence subgroups as modules over the ring of integral modular forms for the full modular group. In many cases these modules are free or decompose at least into well-understood pieces. We apply this to characterize which rings of modular forms are Cohen--Macaulay and to prove finite generation results. These theorems are based on decomposition results about vector bundles on the compactified moduli stack of elliptic curves.Comment: Rewritten introduction, updated references. This article supersedes the algebraic part of arXiv:1609.0926

Journal Staff

In this contribution we describe some of the basic new features of MathWork's System Identification toolbox, version 4.0, which was released in May 1995. The main addition is a graphical user interface (GUI), which allows the user to perform identification, data and model analysis, as well as model validation by less click and mouseless operations. The ideas behind the GUI are explained and its relative merits compared to command driven operations are discussed