Number Theory Web Seminar

This number theory seminar is purely online. Our talks come from various corners of the field and of the world. They are streamed live on Zoom.

Organizers:

  • Michael Bennett (University of British Columbia)

  • Philipp Habegger (University of Basel)

  • Alina Ostafe (UNSW Sydney)


There are no fees, but registration is necessary. To register please follow this link.

Registered users will receive an email a few hours before the talk with a link to the Zoom meeting.

The seminar runs every Thursday. Please note the usual times of the seminar below and in the FAQ Section.

Talks are usually 50 minutes and then time for some questions.

Contact: ntweb.seminar@gmail.com

Please consider the following:

  • Each talk has a unique Zoom meeting-ID that all registered participants receive by email before the talk. You will receive this email from organizers@ntwebseminar.org. Never publicly share this ID or the password.

  • If you did not received an invitation one hour before the talk please check your spam folder. If you cannot find the email there please contact ntweb.seminar@gmail.com.

  • Some mail servers are blocking our domain. Registered participants can click here to get the link to the next talk.

  • To unsubscribe from the mailing list please follow the link at the bottom of the invitation email.

  • Participant's audio is muted by default. You can unmute to ask questions.

  • You can ask questions in the chat window or by unmuting the microphone and asking them directly.

Next talk:



Anish Ghosh, Values of quadratic forms at integer points
(Tata Institute of Fundamental Research)


Thursday, September 30, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 8:30pm Indian Standard Time, 11pm CST)
Friday, October 1, 2021 (1am AEST, 4am NZDT)

Abstract: A famous theorem of Margulis, resolving a conjecture of Oppenheim, states that an indefinite, irrational quadratic form in at least three variables takes a dense set of values at integer points. Recently there has been a push towards establishing effective versions of Margulis's theorem. I will explain Margulis's approach to this problem which involves the ergodic theory of group actions on homogeneous spaces. I will then discuss some new effective results in this direction. These results use a variety of techniques including tools from ergodic theory, analytic number theory as well as the geometry of numbers.


Upcoming talks:

Henryk Iwaniec, Remarks on the large sieve
(Rutgers University)

A talk in honor of John Friedlander's 80th birthday

Special Chairs: Leo Goldmakher (Williams College) and Andrew Granville (University of Montreal)


Thursday, October 7, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 8:30pm Indian Standard Time, 11pm CST)
Friday, October 8, 2021 (2am AEST, 4am NZST)

Abstract: The concept of the large sieve will be discussed in various contexts. The power and limitation of basic estimates will be illustrated with some examples. Recent work on the large sieve for characters to prime moduli will be explained.


Jean-Marc Deshouillers, tba
(University of Bordeaux)


Thursday, October 14, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 8:30pm Indian Standard Time, 11pm CST)
Friday, October 15, 2021 (2am AEST, 4am NZST)

Abstract: tba


Johan Commelin, tba
(Albert–Ludwigs-Universität Freiburg)


Thursday, October 21, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 8:30pm Indian Standard Time, 11pm CST)
Friday, October 22, 2021 (2am AEST, 4am NZST)

Abstract: tba


Dimitris Koukoulopoulos, tba
(University of Montreal)


Thursday, October 28, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 8:30pm Indian Standard Time, 11pm CST)
Friday, October 29, 2021 (2am AEST, 4am NZST)

Abstract: tba


Katherine Stange, tba
(University of Colorado, Boulder)


Thursday, November 4, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, November 5, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Avi Wigderson, Randomness
(Institute for Advanced Study)


Thursday, November 11, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, November 12, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: Is the universe inherently deterministic or probabilistic? Perhaps more importantly - can we tell the difference between the two?

Humanity has pondered the meaning and utility of randomness for millennia.

There is a remarkable variety of ways in which we utilize perfect coin tosses to our advantage: in statistics, cryptography, game theory, algorithms, gambling... Indeed, randomness seems indispensable! Which of these applications survive if the universe had no (accessible) randomness in it at all? Which of them survive if only poor quality randomness is available, e.g. that arises from somewhat "unpredictable" phenomena like the weather or the stock market?

A computational theory of randomness, developed in the past several decades, reveals (perhaps counter-intuitively) that very little is lost in such deterministic or weakly random worlds. In the talk I'll explain the main ideas and results of this theory, notions of pseudo-randomness, and connections to computational intractability.

It is interesting that Number Theory played an important role throughout this development. It supplied problems whose algorithmic solution make randomness seem powerful, problems for which randomness can be eliminated from such solutions, and problems where the power of randomness remains a major challenge for computational complexity theorists and mathematicians. I will use these problems (and others) to demonstrate aspects of this theory.


Myrto Mavraki, tba
(Harvard University)


Thursday, November 18, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, November 19, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Alexei Skorobogatov, tba
(Imperial College London)


Thursday, November 25, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, November 26, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Kiran Kedlaya, tba
(University of California San Diego)


Thursday, December 2, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, December 3, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Samir Siksek, tba
(University of Warwick)


Thursday, December 9, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, December 10, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Sarah Zerbes, tba
(University College London, UK)


Thursday, December 16, 2021 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, December 17, 2021 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Péter Varjú, tba
(University of Cambridge)


Thursday, January 13, 2022 (8am PDT, 11am EDT, 4pm BST, 5pm CEST, 6pm Israel Daylight Time, 9:30pm Indian Standard Time)
Friday, January 14, 2022 (12am CST, 3am AEST, 5am NZST)

Abstract: tba


Sponsors:

We gratefully acknowledge the generous support of:

  • University of Basel (financial support, zoom licence)

  • Max Planck Institute for Mathematics (zoom licence, 2020)

  • University of New South Wales (zoom licence)