Mathematics
Seminar
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Rocky Mountain Algebraic Combinatorics Seminar
Reidemeister-Schreier for rings
Peter Mayr
University of Colorado
In combinatorial group theory the Reidemeister-Schreier Theorem (1927)
asserts that a subgroup of finite index in a finitely presented group is
itself finitely presented. Similar results exist for semigroups (Campbell,
et al., 1996) and associative algebras over fields (Voden, 2009) for the
appropriate interpretation of "finite index". We show a version for
rings: let B be a subring of a finitely presented ring A such that A/B
is finitely generated as a group. Then B is finitely presented. This is
joint work with Nik Ruskuc (University of St. Andrews).
Singularities have simplicial structure
James B. Wilson
Colorado State University
Singularities are zeros in high-dimensional data and general tensors. They
signal solutions to equations, degenerations in geometry, and many other
consequences. They can be difficult to find and are relatively featureless
(what can you say about zero?).
A surprise discovery now equips singularities with a simplicial complex that
controls every operator mapping into a singularity. These "black-holes
in data" are actually rich in discrete structures that we can use to hunt
them down.
Weber 223
4–6 pm
Friday, September 8, 2017
(Refreshments in Weber 117, 3:30–4 pm)
Colorado State University
This is a joint Denver U / UC Boulder / UC Denver / U of Wyoming / CSU seminar that meets biweekly.
Anyone interested is welcome to join us at a local restaurant for dinner after the talks.
PDF version
Previous Seminars:
- May 5, 2017
- Ferdinand Ihringer,
Gavin King
- April 21, 2017
- Vladimir D. Tonchev,
Morgan Rodgers
- April 7, 2017
- Jason Williford,
Anton Betten
- March 24, 2017
- Isabella Novik,
Peter Brooksbank
- March 3, 2017
- Jintai Ding,
Curtis Bennett
- February 17, 2017
- Fatma Karaoglu,
Eric Moorhouse
- February 3, 2017
- Tim Penttila,
James B. Wilson
- December 2, 2016
- Jim Fowler,
Andrew Kelley
- November 11, 2016
- Joseph Gersch,
Joshua Maglione
- October 28, 2016
- John MacLaren Walsh,
Henry Adams
- October 14, 2016
- JM Landsberg,
James B. Wilson
- September 30, 2016
- Alexander Hulpke,
Oscar Levin
- September 16, 2016
- Delaram Kahrobaei,
Amit Patel
- June 23, 2016
- Jason Cantarella,
Michal Adamaszek
- April 29, 2016
- Nick Loehr,
Jason Williford
- April 15, 2016
- Alexander Hulpke,
Klaus Lux
- April 1, 2016
- Eamonn O'Brien,
Izabella Stuhl
- February 19, 2015
- James Wilson,
Anton Betten
- December 4, 2015
- Maria Monks Gillespie,
Dane Flannery
- November 13, 2015
- Richard Green,
Tim Penttila
- October 23, 2015
- Christina Boucher,
Sylvia Hobart
- October 9, 2015
- Josh Maglione,
Ghodratollah Aalipour
- September 25, 2015
- Ross McConnell,
Henry Adams
- September 11, 2015
- James B. Wilson,
Tim Penttila
- May 8, 2015
- Amanda Schaeffer Fry,
Peter Brooksbank
- April 24, 2015
- Heide Gluesing-Luerssen,
Phil DeOrsey
- March 6, 2015
- Felice Manganiello,
Eric Moorhouse
- February 20, 2015
- Anton Dzhamay,
Anton Betten
- February 6, 2015
- Alexander Hulpke,
Morgan Rodgers
- December 5, 2014
- Stefaan De Winter,
Gretchen Matthews
- November 14, 2014
- Greg Coxson,
Tom Dorsey
- October 31, 2014
- Octavio Paez Osuna,
Sylvia Hobart
- October 10, 2014
- Takunari Miyazaki,
Eric Moorhouse
- September 26, 2014
- Elissa Ross,
Anton Betten
- September 12, 2014
- Petr Vojtěchovský,
Alexander Hulpke
- May 9, 2014
- Philip DeOrsey,
Tim Penttila
- April 25, 2014
- William J Martin,
Jason Williford
- April 11, 2014
- Victor Pambuccian,
George Shakan
- March 7, 2014
- Nathan Lindzey,
Jens Harlander
- February 21, 2014
- Ross McConnell,
Anton Betten
- November 22, 2013
- Justin Hughes,
Josh Maglione
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Department of Mathematics Fort Collins, Colorado 80523
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