Rocky Mountain Algebraic Combinatorics Seminar

Recognition and Embedding of Planar Graphs

Ross McConnell
Colorado State University

A graph is planar if it can be drawn in the plane without crossing any edges. Such a drawing is called a planar embedding. Planar graphs and planar embeddings have been studied extensively since the time of Euler. Web sites that challenge visitors to rearrange planar graphs to obtain planar embeddings have been popular with the lay public; see to try your hand at these engaging puzzles. The talk is a survey on interesting properties of planar graphs, as well as recent developments in conceptually simple algorithms for finding planar embeddings, and other related problems that the speaker has worked on.


A random dynamical system and generalized Catalan numbers

Henry Adams
Colorado State University

This talk on joint work with Michal Adamaszek and Francis Motta will be a healthy blend of topology, dynamical systems, and combinatorics. A question about random topological spaces lead us to study the following dynamical system. Fix r > 0 and let X be a uniformly random sample of points from the circle. Define a dynamical system on X which maps a point to its furthest clockwise neighbor in X within distance at most r. What is the expected fraction of periodic points? We were surprised to learn the answer involves generalized Catalan numbers (the number of Dyck paths of bounded height) and their generating functions.


Weber 223
4–6 pm
Friday, September 25, 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:

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