Smashing subcategories and the telescope conjecture – an algebraic approach

We prove a modified version of Ravenel’s telescope conjecture. It is shown that every smashing subcategory of the stable homotopy category is generated by a set of maps between finite spectra. This result is based on a new characterization of smashing subcategories, which leads in addition to a classification of these subcategories in terms of the category of finite spectra. The approach presented here is purely algebraic; it is based on an analysis of pure-injective objects in a compactly generated triangulated category, and covers therefore also situations arising in algebraic geometry and representation theory. Oblatum 23-XI-1998 & 19-V-1999 / Published online: 5 August 1999     

The ‘Light Beam Search’ approach – an overview of methodology applications

The paper gives a general overview of the Light Beam Search (LBS) methodology and applications. LBS enables an interactive analysis of multiple-objective decision problems due to presentation of samples of a large set of non-dominated points, to the decision maker (DM) in each iteration. A local preference model in the form of an outranking relation is used to define the neighborhood of a current non-dominated point the sample comes from. The first current point is obtained by projection of an aspiration point onto the non-dominated set in the direction of a reservation point. The DM can control the search by either modifying the aspiration and reservation points, or by shifting the current point to a selected better point from its neighborhood. The paper describes applications of the approach to several real life problems and discusses observations made while working on these problems. The LBS approach is compared to other existing methods and the class of problems suitable to this methodology is defined.     

On an algebraic version of the Knizhnik–Zamolodchikov equation

A difference equation analogue of the Knizhnik?CZamolodchikov equation is exhibited by developing a theory of the generating function H(z) of Hurwitz polyzeta functions to parallel that of the polylogarithms. By emulating the role of the KZ equation as a connection on a suitable bundle, a difference equation version of the notion of connection is developed for which H(z) is a flat section. Solving a family of difference equations satisfied by the Hurwitz polyzetas leads to the normalized multiple Bernoulli polynomials (NMBPs) as the counterpart to the Hurwitz polyzeta functions, at tuples of non-positive integers. A generating function for these polynomials satisfies a similar difference equation to that of H(z), but in contrast to the fact that said polynomials have rational coefficients, the algebraic independence of the usual Hurwitz zeta functions is proven, and the Hurwitz polyzeta functions are shown to satisfy no algebraic relations other than those arising from the shuffle relations. The values of the NMBPs at z=1 provide a regularization of the multiple zeta values at tuples of negative integers, which is shown to agree with the regularization given in Akiyama et al. (Acta Arith. 98:107?C116, 2001). Various elementary properties of these values are proven.     

Corrigendum to “New algebraic properties of an amalgamated algebra along an ideal”

At some point, after publication, we realized that Proposition 4.1(2) and Theorem 4.4 in [2 D’Anna, M., Finocchiaro, C. A., Fontana, M. (2016). New algebraic properties of an amalgamated algebra along an ideal. Commun. Algebra 44(5):1836–1851.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]] hold under the assumption (not explicitly declared) that B = f(A)+J. Furthermore, we provide here the exact value for the embedding dimension of A?^fJ, also when B≠f(A)+J, under the hypothesis that J is finitely generated as an ideal of the ring f(A)+J.     

An algebraic approach to the vector ε-algorithm

The vector -algorithm is obtained from the scalar -algorithm by taking the pseudo-inverse of a vector instead of the inverse of a scalar. Thus the vector -algorithm is known only through its rules contrarily to the scalar -algorithm and some other extrapolation algorithms.The aim of this paper is to provide an algebraic approach to the vector -algorithm.     

Diagonally implicit Runge—Kutta methods for differential algebraic equations of indices two and three

Diagonally implicit Runge-Kutta methods satisfying additional order conditions are examined. These conditions make it possible to solve differential algebraic equations of indices two and three to higher accuracy. Advantages of the proposed methods over other known techniques are demonstrated using test problems.     

Run up flow of an incompressible micropolar fluid between parallel plates – A state space approach

In this paper, we study the run up flow of an incompressible micropolar fluid between two horizontal infinitely long parallel plates. Initially a flow of the fluid is induced by a constant pressure gradient until steady state is reached. After the steady state is reached, the pressure gradient is suddenly withdrawn while the two plates are impulsively started with different velocities in their own plane. Using the Laplace transform technique and adopting the state space approach, we obtain the velocity and microrotation components in Laplace transform domain. A standard numerical inversion procedure is used to find the velocity and microrotation in space-time domain for various values of time, distance, material parameters and pressure gradient. The variation of velocity and microrotation components is studied and the results are illustrated through graphs. It is observed that the micropolarity parameter has a decreasing effect on velocity component. It is also found that as the gyration parameter increases there is a decrease in microrotation component and an increase in velocity component.     

Is there an easy algebraic characterisation of¶universal proper G-spaces?

We shall study properties of groups having finite cohomological dimension relative to the family of all finite subgroups. We also compare these groups with those satisfying various suggested algebraic analogues to group-actions on finite dimensional proper G-spaces. Received: 15 March 2000     

An algebraic approach to finding the Fermat–Torricelli point

Using a calculus and an algebraic approach, the Cartesian coordinates of the Fermat–Torricelli point are deduced for triangles with no internal angle greater than 120°. Although in theory, the deduction of these coordinates could be made ‘by hand’, in practice it is very laborious to obtain them without the aid of mathematical computer software, but with human guidance, since there are mathematical artifices not yet incorporated into the software. It is also shown that these coordinates can be conveniently expressed in terms of the side lengths and the area of the triangle. These coordinates are contrasted with the coordinates of a similar point: one whose sum of the squares of the distances to the vertices of an arbitrary triangle is a minimum.     

On linear combinatorics I. Concurrency—An algebraic approach

This article is the first one in a series of three. It contains concurrency results for sets of linear mappings of with few compositions and/or small image sets. The fine structure of such sets of mappings will be described in part II [3]. Those structure theorems can be considered as a first attempt to find Freiman-Ruzsa type results for a non-Abelian group. Part III [4] contains some geometric applications.Dedicated to the memory of P. ErdsResearch partially supported by HU-NSF grants OTKA T014302 and T019367.     

Interaction of phase-transformations and plasticity – a multi-phase micro-sphere approach

We present an efficient model for the simulation of solid to solid phase-transformations in polycrystalline materials. As a basis, we implement a scalar-valued Gibbs-energy-barrier-based phase-transformation model making use of statistical physics. In this work, we particularly adopt the model for the simulation of phase-transformations between an austenitic parent phase and a martensitic tension and compression phase. The incorporation of plasticity phenomena is established by enhancing the Helmholtz free energy functions of the material phases considered, where the plastic driving forces acting in each phase are derived from the overall free energy potential. The coupled model is embedded into a micro-sphere formulation in order to simulate three-dimensional boundary value problems—a technique well-established in the context of computational inelasticity at small strains. It is shown that the model is capable of reflecting experimentally observed behaviour. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the convergence of genetic algorithms – a variational approach

A variational approach is introduced to study the existence and uniqueness of stationary states and (exponential) stability of genetic algorithms with mutation and interactive selection.Mathematics Subject Classification (2000): 35J20 (90C30, 92D25, 35J60, 31C25)     

A new algebraic approach to the Szegő-Widom limit theorem

We give another proof of the Szeg\H{o}–Widom Limit Theorem. This proof relies on a new Banach algebra method that can be directly applied to the asymptotic computation of the Toeplitz determinants. As a by-product, we establish an interesting identity for operator determinants of Toeplitz operators, namely if are certain matrix valued functions defined on the unit circle, then

Visualization of two dimensional to three dimensional transformations – exploration through technology

A small class of functions is described that easily lend themselves to two-dimensional and three-dimensional visualizations at the basic calculus level. The intended audience is those educators involved in the instruction of elementary calculus. This note is an educational piece that begins with the question: ‘What happens if a function defined on a short interval in the first quadrant is rotated about an axis? This question is answered visually using a graphical software package Mathematica®.     

Perturbation of systems of linear algebraic equations ∗

A classical perturbation result for nonsingular systems of linear algebraic equations is extended to general consistent systems under any norm. An optimal perturbation result is also obtained for general linear least squares problems under a Euclidean norm.     

Buckling Analysis of Carbon Nanotubes – Application of a concurrent atomistic-continuum multiscale approach

In this work, a concurrent atomistic-continuum multiscale approach is applied in order to analyse the buckling behaviour of carbon nanotubes. In particular, the bridging domain method that is grounded on an overlapping domain partitioning scheme with an energy-based blending of the subdomains is used. The atomistic subdomain is modelled by means of a molecular statics approach and the continuum subdomain is handled using the finite element method. Outcomes of numerical simulations of defective single-walled carbon nanotubes under bending load are presented. More specifically, the impact of variably located Stone-Wales defects on the buckling behaviour of a nanotube is studied using the concurrent multiscale approach. The results of the multiscale model are validated against a full atomistic molecular statics simulation. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)