Mathematical Colloquim
PROGRAM
ODELJENJE ZA MATEMATIKU MATEMATICKOG INSTITUTA SANU |
OPSTI MATEMATICKI SEMINAR NA MATEMATICKOM FAKULTETU U BEOGRADU |
-- PROGRAM ZA JUN 2007 --
Petak, 01. jun 2007. u 12h, sala 2 MI
SANU:
Adolf Knol, National Library of the Czech Republic
TOWARDS A EUROPEAN DIGITAL LIBRARY OF MANUSCRIPTS
Abstract: The Czech National Library together with 17 full partners and
other ca. 10 associated partners from many European countries have expressed
the willingness to build a distributed digital library of manuscripts that
would provide seamless access to dispersed digital manuscript resources. It
will be based on the Czech Manuscriptorium DL that aggregates even today ca.
1,000,000 digitized pages from more than 30 Czech and foreign institutions.
By the end of the project, the user will have access to more than 5 million
digitized pages and other data as well as to rich catalogue descriptions.
The paper will discuss the methods and techniques used to achieve this goal
and to support various types of partners and researchers.
Petak, 01. jun 2007. u 14h, sala 2, SANU, BG:
Yuri Fedorov, Departament de Matematica I, Universitat Politecnica de
Catalunya, Barcelona, Spain
CLOSED AND ALGEBRAIC CLOSED GEODESICS ON AN ELLIPSOID
Abstract: One of the best known classical integrable systems is the geodesic
motion on a triaxial ellipsoid Q in R^3. Apparently, until recently there
was no explicit description of closed geodesics on $Q$.
We propose a simple method of explicit description of families of such
geodesics on an ellipsoid in R^n that are cut out by algebraic surfaces in
$R^n (so called algebraic closed geodesics). Such geodesics are shown to be
either connected components of spatial elliptic curves or of rational
curves.
Our approach is based on elements of the Weierstrass--Poincare reduction
theory for hyperelliptic tangential covers of elliptic curves and a
remarkable isomorphism between geodesics on a quadric and stationary
solutions of the KdV equation. For the case of 3-fold and 4-fold coverings,
explicit formulas for the cutting algebraic surfaces will be provided.
We shall also discuss a relation of this approach with the criteria
developed recently by Dragovic and Radnovic.
Petak, 08. jun 2007. sala 2 MI SANU:
Natasa Sladoje, Fakultet tehnickih nauka, Novi Sad
ON ANALYSIS OF DISCRETE SPATIAL FUZZY SETS IN 2 AND 3 DIMENSIONS
Abstract: The advantages of representing objects in images as fuzzy spatial
sets are numerous and have lead to increased interest for fuzzy approaches
in image analysis. Fuzziness is an intrinsic property of images. It is
additionally introduced in digital image processing by discretization, and
as a natural outcome of most imaging devices. Preservation of fuzziness
implies preservation of important information about objects and images.
Therefore, fuzziness should, in general, be kept and utilized as long as
possible when analyzing the image data.
In this talk, main results of our research related to the development of
shape analysis methods that can be applied to fuzzy segmented images in 2D
and 3D will be presented. We have studied a number of known shape
descriptors: (1) geometric moments; (2) the signature of a shape based on
the distance from the shape centroid; (3) the measurements of area,
perimeter, and compactness, as well as of volume, surface area, and
sphericity. We have shown, either theoretically, or through statistical
studies, that the precision of estimation of the studied features of a
continuous shape is increased if a fuzzy discrete representation of the
shape is used, instead of a crisp one. In addition, we have designed a
defuzzification method based on feature invariance, utilizing the improved
estimates of shape characteristics from fuzzy sets to generate crisp
discrete shapes with the most similar shape characteristics.
The presented results can be applied wherever precise estimates of shape
properties are equired, especially in conditions of limited spatial
resolution.
Petak, 15. jun 2007. u 14h, sala 2, MI SANU, BGD:
Djordje Kadijevic, Matematicki Institut SANU
O KOMPLEKSNOSTI ISTRAZIVANJA U NASTAVI MATEMATIKE
Rezime: U predavanju se prikazuju specificnosti istrazivanja u nastavi
matematike i ukazuje na njihovu kompleksnost. Ova kompleksnost se detaljno
ilustruje za temu povezivanje proceduralnog i konceptualnog matematickog
znanja posredstvom CAS (softvera za racunarsku algebru).
Petak, 22. jun 2007. u 14h, sala 718, MF BG:
Miljan Knezevi?, Matematicki fakultet, Beograd
ON THE QUASI-ISOMETRIES OF HARMONIC QUASICONFORMAL MAPPINGS
Abstract: We prove versions of the Ahlfors-Schwarz lemma for
quasiconformal euclidean harmonic functions and harmonic mappings with
respect to the Poincaré metric.
Predavanja ce se odrzavati na Matematickom Institutu (sala 2), petkom sa pocetkom u 14 casova. Odeljenje za matematiku je opsti seminar sa najduzom tradicijom u Institutu.
Svakog meseca, jedno predavanje ce biti odrzano na Matematickom Fakultetu u terminu koji ce biti posebno odredjen.
Molimo sve zainteresovane ucesnike u radu naucnih sastanaka da posebno obrate paznju na vreme odrzavanja svakog sastanka. Na Matematickom fakultetu su moguce izmene termina.
Obavestenje o programu naucnih sastanaka ce biti objavljeno na oglasnim tablama MI (Beograd), MF (Beograd), PMF (Novi Sad), PMF (Nis) i PMF (Kragujevac).
Odeljenje za matematiku Matematickog instituta SANU
Stevan Pilipovic
Opsti matematicki seminar na Matematickom fakultetu u Beogradu,
Sinisa Vrecica
Ako zelite da se obavestenja o Vasim naucnim skupovima pojave u Newsletter of EMS (European Mathematical Society) i na Internetu na lokaciji EMS, onda se obratite na emsvesti@mi.sanu.ac.yu gde cete dobiti format obavestenja.