Seminar on Applied Mathematics
Peter Rowlinson, University of Stirling, Stirling, Scotland, U.K.
THE MULTIPLICITY OF GRAPH EIGENVALUES
Abstract: We show how star complements can be used to determine a sharp upper bound for the multiplicity of a graph eigenvalue other than -1 or 0. The result is an analogue for arbitrary graphs of the so-called absolute bound for strongly regular graphs. We establish a similar bound for regular graphs; in this case, the graphs for which the bound is attained are precisely the extremal strongly regular graphs.
Vladimir Bukvic, Vojna Akademija, Beograd
SIMULACIONO MODELIRANJE ORGANIZACIONE STRUKTURE HIJERARHIJSKOG VISENIVOJSKOG LOGISTICKOG SISTEMA
(zajednicki sastanak sa Seminarom Katedre za matematiku, kibernetiku i informacione sisteme FON-a)
OBAVESTENJE:Utorak, 3.6.2003. u 11h, biblioteka MI SANU :
Adelina Georgescu, predsednica rumunskog udruzenja za industrisku i primenjenu matematiku (ROMAI), Faculty of Mathematics and Computer Sciences University of Pitesti, Romania
METHODS BASED ON FOURIER SERIES IN HYDROMAGNETIC STABILITY THEORY
Abstract: In linear stability of fluid flows and equilibria subject to several effects (e.g. temperature, concentration, magnetic field) the governing ordinary differential equations are of high order (usually more than 10) and contain several (usually more than three) parameters. In addition, the equations are not selfadjoint and the corresponding eigenvalues are not simple. Finally, the boundary conditions are quite complicate. As a consequence the Fourier series expansion methods of Galerkin type based on total sets of expansion functions satisfaying all boundary conditions are no longer appropriate. This is why we used Budiansky--DiPrima method in which the expansion functions do not satisfy all boundary conditions, thus introducing some constraints. We reveal the main steps in its application to magnetic convections. We also show the advantages and the peculiarities of this method if applied to the associated variational setting.