Combinatorial Potlatch 2013
University of Victoria
Saturday, November 23, 2013

About the Combinatorial Potlatch

The Combinatorial Potlatch is an irregularly scheduled, floating, one-day conference. It has been held for many years at various locations around Puget Sound and southern British Columbia, and is an opportunity for combinatorialists in the region to gather informally for a day of invited talks and conversation. While most who attend work in, or near, the Puget Sound basin, all are welcome.  Typically there are three talks given by speakers who are visiting or new to the area, along with breaks for coffee and lunch. Many participants remain for dinner at a local restaurant or pub.

The American Heritage Dictionary defines "potlatch" as: A ceremonial feast among certain Native American peoples of the northwest Pacific coast, as in celebration of a marriage or an accession, at which the host distributes gifts according to each guest's rank or status. Between rival groups the potlatch could involve extravagant or competitive giving and destruction by the host of valued items as a display of superior wealth. [Chinook Jargon, from Nootka p'achitl, to make a potlatch gift.]

This fall's Potlatch is being hosted by the Department of Mathematics and Statistics at University of Victoria at their main campus in Victoria, British Columbia on Saturday, November 23, 2013.

Significant funding is being provided by Pacific Institute for the Mathematical Sciences (PIMS) and the Department of Mathematics and Statistics at University of Victoria. Their support is gratefully acknowledged.

More info, including a history and links to previous Potlatches, is at The Combinatorial Potlatch Home Page.


All talks will be held in Clearihue A127, with registration and breaks nearby. See the Getting There section for exact locations and directions.

  • 10:00 AM Registration, Bagels and Coffee
  • 11:00 AM Richard Hoshino, Applying Combinatorics to Inspire Change
  • 12:00 PM Lunch
  •   2:00 PM Dillon Mayhew, Characterizing Representable Matroids
  •   3:00 PM Cookies, Coffee and Cokes
  •   3:30 PM Jérémie Lumbroso, Analytic Random Generation of Combinatorial Objects
  •   4:30 PM Happy Hour, Dinner

Talks and Abstracts

Dillon Mayhew, Victoria University of Wellington, New Zealand

Title: Characterizing Representable Matroids

Abstract: Matroids abstract the notions of linear/geometric/algebraic dependence. More specifically, a matroid consists of a finite collection of points, and a distinguished family of dependent subsets. If we take a finite collection of vectors from a vector space, and distinguish the linearly dependent subsets, then the result is a matroid, and we say that such a matroid is representable. The original motivating problem in matroid theory involves deciding which matroids are representable and which are not. A large fraction of the research in the area has been driven by this problem.

This talk will be an introduction to matroid theory, and an examination of two different methods for characterizing representable matroids: excluded-minor characterizations and formal languages. No knowledge of matroids will be assumed.

Richard Hoshino, Quest University Canada

Title: Applying Combinatorics to Inspire Change

Abstract: In this informal talk, I will share the "existential crisis" I encountered during graduate school, when I realized that I was spending hours and hours each day working on graph theory problems that were of interest to just a handful of pure mathematicians. While I knew that I was making a difference through my teaching and outreach, I yearned to impact society through my research as well.

Over the past seven years, I've learned that a combinatorialist can indeed make a difference, and I'll share some ways in which I've applied simple ideas in discrete mathematics to inspire real change: reducing wait times at Canadian airports; implementing a roommate-matching algorithm for students at my university; and helping a billion-dollar professional baseball league design a regular-season schedule to cut costs and reduce greenhouse gas emissions.

Jérémie Lumbroso, Simon Fraser University

Title: Analytic Random Generation of Combinatorial Objects

Abstract: Combinatorial random generation consists in uniformly drawing a combinatorial object from other objects within a given class - and to preferably do so efficiently. Given a specific combinatorial class (for instance: permutations, binary trees, etc.), a particular, very efficient method to randomly generate objects of that class usually exists, which usually exploits the known properties of objects. But what if we would like to be able to generate any combinatorial class simply from its symbolic specification? This gives rise to the notion of automatic random generation.

In the last decade, a recent, incredible development of analytic combinatorics (wherein combinatorial objects are studied through the analytic properties of their generating functions) has been Boltzmann sampling. This is an automatic random generation method, which is very efficient, and uses the curious notion of evaluating the generating function of a class to determine the probabilities of randomly generating its objects.

This talk will present a survey of this concept, and showcase some of its advanced refinements.


The Combinatorial Potlatch has no permanent organization and no budget. And we like it that way. Consequently, there are no registration fees because we wouldn't know what to do with them. You are on your own for meals and lodging, and the sponsoring institutions provides facilities, food for the breaks and some support for speakers' travel. So expressions of appreciation to the speakers and the hosts are preferred and especially encouraged. Thanks.

Getting There

Victoria is on Vancouver Island, so a ferry or float plane will likely be part of your travel plans. Specific information about travel from Seattle or Vancouver can be found here. And this page has detailed listings for various services. Float planes and the Black Ball ferry (the MV Coho from Port Angeles) arrive in the harbour in central Victoria, and so place you within walking distance to many hotels. The morning run of the MV Coho should give you time to come directly to the talks if you take a taxi after clearing immigration.

The University of Victoria Campus is located away from the central downtown area. So if you wish to overnight where there are more hotels and restaurants, you will need to arrange transportation to/from the campus (bus, taxi). The number 4 bus departs from near the Marriott and goes to the campus.

If you are driving, Parking Lot 1 is suggested as your best option. $2 for the day.

Talks will be held in the Clearihue Building, inside the ring road on the campus map.


No special arrangements have been made for lodging. Here are some suggestions.

The James Bay Inn
It is a 10-20 minute walk to the bus to UVic, unless you transfer.
Helm's Inn
Same general area as James Bay Inn. Maybe a bit closer to town.
Best Western Plus Inner Harbour
Close to ferry landing.
Days Inn Victoria
Close to ferry landing.
Marriott Inner Harbour
Convenient public bus to campus.
Chateau Victoria
Close to Marriott, but cheaper.
Swans Suite Hotel
Lots of character, but try not to get a room right over the pub.
Bedford Regency
Best Western Carleton Plaza

Dining and Happy Hour

You are encouraged to join other conference participants at the various meals and other events we are planning for the day. Details here as we have them.

Lunch Locations
Happy Hour, Dinner
At the Canoe Brewpub, after the conclusion of the day's program. We have space reserved.


  • Rob Beezer, University of Puget Sound, beezer (at) ups (dot) edu, Communications Chair
  • Nancy Ann Neudauer, Pacific University, nancy (at) pacificu (dot) edu, Program Chair
  • Gary MacGillivray, U of Victoria, gmacgill (a) uvic (dot) ca, Local Arrangements Chair
Last updated: November 9, 2013,