Hyperbolic towers and independent generic sets in the theory of free groups

We use hyperbolic towers to answer some model theoretic questions around the generic type in the theory of free groups. We show that all the finitely generated models of this theory realize the generic type $p_0$, but that there is a finitely generated model which omits $p_0^{(2)}$. We exhibit a finitely generated model in which there are two maximal independent sets of realizations of the generic type which have different cardinalities. We also show that a free product of homogeneous groups is not necessarily homogeneous.Comment: to appear in Proceedings of the conference "Recent developments in Model Theory", Notre Dame Journal of Formal Logi

Homogeneity in the free group

We show that any non abelian free group \F is strongly $\aleph_0$-homogeneous, i.e. that finite tuples of elements which satisfy the same first-order properties are in the same orbit under \Aut(\F). We give a characterization of elements in finitely generated groups which have the same first-order properties as a primitive element of the free group. We deduce as a consequence that most hyperbolic surface groups are not $\aleph_0$-homogeneous.Comment: 26 page

Higher order Hamiltonian fluid reduction of Vlasov equation

From the Hamiltonian structure of the Vlasov equation, we build a Hamiltonian model for the first three moments of the Vlasov distribution function, namely, the density, the momentum density and the specific internal energy. We derive the Poisson bracket of this model from the Poisson bracket of the Vlasov equation, and we discuss the associated Casimir invariants

Hamiltonian closures for fluid models with four moments by dimensional analysis

Fluid reductions of the Vlasov-Amp{\`e}re equations that preserve the Hamiltonian structure of the parent kinetic model are investigated. Hamiltonian closures using the first four moments of the Vlasov distribution are obtained, and all closures provided by a dimensional analysis procedure for satisfying the Jacobi identity are identified. Two Hamiltonian models emerge, for which the explicit closures are given, along with their Poisson brackets and Casimir invariants

Kitap sevgisi

Taha Toros Arşivi, Dosya No: 111-Kütüphaneler. Not: Gazetenin "Edebiyat Konuşmaları" köşesinde yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Form follows meaning, meaning follows form: Surrendering the innocence of design

Creativity is a loaded concept, which we seem to assign unconditional merit. The danger in this arises when the allure and momentum of creative processes obscure underlying project agendas. If we consider designed images, products, and environments to be part of the broader cultural setting, then designers are accountable for the paradigms that we enable through our work. As systems- oriented designers, we cannot hide behind the agendas of our clients; rather, we must view each project as a powerful act of cultural meaning making, in which we share creative agency. In this paper, we will briefly examine how changes taking place within the field of design may ultimately influence what we construct as our experienced realities, and also how the positioning of creative practices within a socio-economic system can determine how they are employed in cultural production