Ett informationsblad från matematiska institutionen vid Linköpings universitet. Material till Lite Mat lämnas till Maud Lindström litemat@mai.liu.se senast torsdagar kl 12.00.

Vi har dessutom ett arkiv av gamla nummer.

***LITE MAT***

Ett informationsblad från matematiska institutionen vid Linköpings universitet

v9 2003

Matematiska kollokviet

Onsdagen den 5 mars, kl. 13.00-14.00 talar Andreas Bette, KTH syd

On spinning objects in (special) relativity

Sammanfattning:

-A relativistic (twistor) phase space formulation of the dynamics of a spinning electrically charged massive particle in an external electro-magnetic field will be presented. The function used to generate such a dynamics is chosen so that it corresponds to the (second order) Dirac operator.
-If time permits, a relativistic (twistor) action integral will be presented describing a free massive spinning (no Grassman variables are needed) string.

Lokal: ISY/MAI:s seminarierum Glashuset, ing 25.

Välkomna!

Anders Björn,
Vladimir Kozlov,
Svante Linusson och
Stefan Rauch-Wojciechowski

Analysseminarium

Fredagen den 21 februari, kl. 13.15-15.00 talar Professor Nikolay Kuznetsov, St Petersburg

Unsteady water waves in the presence of submerged obstacles

Abstract: The time-dependent problem provides a natural approach to water waves because various steady-state statements usually arise as limiting cases of the unsteady problem. Main results concerning the latter problem were obtained by A. Friedman & M. Shinbrot and R. Garipov under assumption that the obstacle is totally submerged (uneven bottom and/or floating bodies). Their results will be outlined in the talk. Obtaining similar results in the case of surface-piercing obstacles is still an open question. The corresponding difficulties will be discussed.

Lokal: ISY/MAI:s seminarierum Glashuset, ing 25

Välkomna!
Vladimir Kozlov

Seminarier i numerisk analys

Tisdagen den 25 februari kl 13.15 talar Katarina Blom från Chalmers i seminarierummet Beurling om

Information Retrieval using Krylov Subspace Methods

En sammanfattning av föredraget finns på http://www.mai.liu.se/~laeld/blom-abstract.ps

Fredagen den 28 februari kl 10.15 talar Nicola Mastronardi från Istituto per le Applicazioni del Calcolo "M.Picone" sez. Bari, Italien, om

On Computing the Eigenvalues of Large Dense Matrices

Seminariet äger rum i Glashuset.

Seminarium i statistik

Torsdagen den 27 februari kl 15.15 talar Erik Löfving, Linköpings universitet.

Titel: Data models for physical flow data - a short introduction to the fundamental concepts of database systems.

Abstract: Assessment of physical flows play a key role in industrial ecology. Several tools, such as SFA, MFA and I-O analysis, deal directly with such flows. In this paper, we use ideas developed for multidimensional databases and the Data Cube concept to demonstrate how flow data, and calculations involving such data, can be organised in an efficient way. In particular, we show that the most widespread conceptual models for SFA and MFA are merely special cases of a generic Data Cube model.

Lokal: Glashuset

Välkomna!
Lars Walter

Till alla de som är intresserade av kursen i grundläggande kombinatorik 5p

Schemat är nu beslutat och det kommer att bli några intensivläsningstillfällen enligt nedan.

24 april 13-17 Beurling
25 april 8-12 Glashuset
5 maj 13-17 Glashuset
6 maj 8-12 Glashuset???
20 maj 13-17 Beurling
21 maj 8-12 Beurling
2 juni 13-17 Glashuset
3 juni 8-12 Beurling
3 juni 13-17 Glashuset (studentseminarier)
4 juni 8-12 Glashuset (studentseminarier)

En extra dubbeltimme kommer att ges utanför ovanstående schema för de som saknar relevanta förkunskapar om pomängder och lattice.

Lokalerna är preliminära och kan komma att ändras. Ändringar skickas till alla de som har anmält sitt intresse till kursen till mig. Det kommer också att läggas upp på kurshemsidan http://www.mai.liu.se/foutb/linusson03.html

Välkomna!

Svante Linusson

Presentation av examensarbete

Måndag den 24 februari kl. 13.15 - 14.00, presenterar Gustav Nordh sitt examensarbete

Generalization of Skolem Sequences

A classical Skolem sequence is a sequence a1, a2,...,a2n where ai is in A = 1...n . Each ai occurs exactly twice in the sequence and the two occurrences are exactly ai positions apart. A set A that can be used to produce classical Skolem sequences is called a classical Skolem set. The problem of deciding which sets of the form A = 1...n that are classical Skolem sets was solved by Thoralf Skolem in the late 1950's. We study the natural generalization where A is allowed to be any set (or even multiset) of n positive integers. We give necessary conditions for the existence of Skolem sets of this generalized form. We conjecture these necessary conditions to be sufficient, and give strong computational evidence in favor of our conjecture.We prove that the existence question for an even more generalized form of Skolem sets are NP-complete. We answer an existence question for permutations similar to the existence question for classical Skolem sequences.

We also look at enumerative aspects, the number of multi Skolem sequences (multisets allowed) of order n are proved to be (2n-1)!!

Handledare och examinator: Svante Linusson
Opponent: Daniel Hedberg

Lokal: Seminarierum Beurling

Välkomna!

Mer information om MAI finns på under MAIs hemsida
Material till Lite Mat lämnas till Maud Lindström senast torsdagar kl 12.00.
Tel 013-281405, Fax 013-100746, Email: litemat@mai.liu.se

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