On existence of canonical GG-bases

We describe a general method for expanding a truncated G-iterative Hasse-Schmidt derivation, where G is an algebraic group. We give examples of algebraic groups for which our method works

Existentially closed fields with G-derivations

We prove that the theories of fields with Hasse-Schmidt derivations corresponding to actions of formal groups admit model companions. We also give geometric axiomatizations of these model companions.Comment: In version 2: new proof of (the current) Proposition 3.3

A note on integrating group scheme actions

We prove a non-integrability result concerning iterative derivations on projective line, where the iterative rule is given by a non-algebraic formal group

The dawn of mathematical biology

In this paper I describe the early development of the so-called mathematical biophysics, as conceived by Nicolas Rashevsky back in the 1920's, as well as his latter idealization of a "relational biology". I also underline that the creation of the journal "The Bulletin of Mathematical Biophysics" was instrumental in legitimating the efforts of Rashevsky and his students, and I finally argue that his pioneering efforts, while still largely unacknowledged, were vital for the development of important scientific contributions, most notably the McCulloch-Pitts model of neural networks.Comment: 9 pages, without figure

Integrating Hasse-Schmidt derivations

We study integrating (that is expanding to a Hasse-Schmidt derivation) derivations, and more generally truncated Hasse-Schmidt derivations, satisfying iterativity conditions given by formal group laws. Our results concern the cases of the additive and the multiplicative group laws. We generalize a theorem of Matsumura about integrating nilpotent derivations (such a generalization is implicit in work of Ziegler) and we also generalize a theorem of Tyc about integrating idempotent derivations

Erste Erkenntnisse zum ANFA-Abkommen: ANFA ermöglicht Finanzierung von Bankenabwicklungen durch nationale Zentralbanken

Anfang Februar 2016 veröffentlichte die EZB ein bis dato geheimes Abkommen namens ANFA. Das Abkommen über die Netto-Finanzanlagen ist ein privatrechtlicher Vertrag zwischen den 20 Mitgliedern des Eurosystems und legt diesen generelle Obergrenzen für ihre nicht geldpolitischen Bilanzaktivitäten auf. In seinem Kommentar legt Daniel Hoffmann nahe, dass das Abkommen den nationalen Zentralbanken erlaubt, Bankenabwicklungen zu finanzieren