Rocky Mountain Algebraic Combinatorics Seminar

Representations of generalized nil-Temperley--Lieb algebras

Richard Green
University Of Colorado, Boulder

Generalized nil-Temperley-Lieb algebras are certain associative algebras defined by generators and relations. The defining relations resemble those of the generalized Temperley-Lieb algebras, but with certain products of generators set equal to zero. I will explain how to use the combinatorics of heaps to define representations of the nil versions of the algebras, and describe some of their properties.


New families of strongly regular graphs

Tim Penttila
Colorado State University

Strongly regular graphs are those finite, regular, non-complete, non-null graphs such that the polynomial algebra in the adjacency matrix has the minimum dimension (three), and they also have a (simpler) combinatorial definition. In 1982, Chris Godsil and Brendan McKay invented a construction technique for co-spectral graphs (those where the adjacency matrices have the same multiset of eigenvalues). We apply their technique to graphs arising in finite geometry from quadrics in binary projective spaces to obtain new families of strongly regular graphs with the same parameters as the collinearity graphs of the quadrics. Related work by Bill Kantor, Aida Adiab and Willem Haemers and Alice Huiman Wa will also be mentioned in passing.

This is joint work with Susan Barwick, Wen-Ai Jackson.


Weber 223
4–6 pm
Friday, November 13, 2015
(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.

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Previous Seminars:

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

Department of Mathematics
Fort Collins, Colorado 80523