Kolloquium des Instituts für Mathematik und Informatik
Das Kolloquium ist eine gemeinsame Veranstaltung aller Arbeitsgruppen des Instituts für Mathematik und Informatik. Es findet in der Regel dreimal pro Semester statt. Das Kolloquium richtet sich an alle Mitglieder unseres Instituts, an Studierende in unseren Master-Studiengängen, an fortgeschrittene Studierende unserer Bachelor-Studiengänge, sowie an mathematisch interessierte Mitglieder anderer Institute der Mathematisch-Naturwissenschaftlichen Fakultät.
Alle interessierten Zuhörer sind immer herzlich willkommen.
The Colloquium is a regular event staged by all groups of the Institute of Mathematics and Computer Science. It usually takes place six times a year. It is addressed to all members of the faculty, postdocs, PhD students, master's students, and advanced bachelor's students, as well as colleagues from other institutes of the Faculty of Mathematics and Natural Sciences, who are interested in mathematics.
Everyone is welcome to attend our Colloquium.
Please let us know in advance which technical equipment you plan to use. We have rooms with large chalkboard, with a beamer, or both (also for simulaneous use).
The audience of your talk includes faculty and students of diverse mathematical backgrounds (pure & applied math, and computer science).
We kindly request that your talk be about 50 minutes in length, aimed at a general audience, and accessible to graduate students.
In particular, your talk should not be directed towards an audience of experts as is common in area-specific seminars. It is not necessary to present details on your latest research results. However, discussing their global meaning and consequences can be very valuable, and giving some historical perspective of your topic and explaining why it is of interest to you and your community can be an excellent start. Please do not feel obliged to explain all ideas in a fully rigorous way.
Indeed, most of the audience will very much appreciate a slightly informal approach to new topics and concepts.
We thank you very much in advance, and we are looking forward to your talk!
Genus and Unknotting Number of a Knot
30.4.2018, 16:00 Uhr
A knot is closed curve in R³. Every knot bounds an orientable surface, and the minimal genus of such a surface is called the genus of the knot. Every knot can be transformed into the trivial knot by a finite number of crossing changes. The minimal number of crossing changes is called the unknotting number. We will introduce these invariants of knots and discuss some properties and open questions.
Stefan Friedl studied Mathematics and Physics in Regensburg and later at Brandeis University in Massachusetts. He obtained a Ph.D in Mathematics from Brandeis University in 2003. He held postdoc positions in Munich, Houston, and Montreal. He became assistant professor at University of Warwick, then professor at University of Cologne, and since he is 2013 professor at University of Regensburg.
Stefan Friedl's research interests are Knot theory, low–dimensional topology, symplectic 4–manifolds, and related algebra.