## Saturday October 25, 2014

This is the 16th Northwest Probability Seminar, a one-day mini-conference organized by the University of Washington, the Oregon State University, the University of British Columbia, the University of Oregon, and the Theory Group at Microsoft Research. This year the conference is being hosted at Microsoft.

Supported by **Microsoft Research** and the **Pacific Institute for the Mathematical Sciences** (PIMS).

The **Birnbaum**** Lecture in Probability** will be given by **Srinivasa Varadhan** (New York University). [Past Birnbaum speakers] The other speakers will be Ioana Dumitriu (University of Washington), Alexander Holroyd (Microsoft Research), Tim Hulshof (University of British Columbia), and Benjamin Young (University of Oregon).

There is no registration fee. Participants are requested to email David.Wilson@microsoft.com in advance so that name tags and adequate food may be arranged for. Breakfast, lunch, and coffee will be free.

The talks will take place in Building 99 at Microsoft. Parking at Microsoft is free.

(The Northwest Probability Seminar at Microsoft in 2012.)

## Schedule (tentative)

9:00 - 11:15 |
Coffee and muffins |

11:15 - 11:50 | talk -- Alexander Holroyd |

12:00 - 12:35 | talk -- Tim Hulshof |

12:40 - 1:40 | Lunch (catered) |

1:40 - 2:15 | Probability demos and open problems |

2:20 - 3:15 |
Birnbaum lecture -- |

3:25 - 4:00 | talk -- Benjamin Young |

4:05 - 4:35 | Tea and snacks |

4:35 - 5:10 | talk -- Ioana Dumitriu |

6:00 - | Dinner (no-host, at Haiku sushi & seafood buffet, downtown Redmond) |

On Sunday October 26, weather permitting, there will be a "math hike".

## Directions

From the north: Take I-5 south, then I-405 south, then WA-520 east.

From the south: Take I-5 north, then I-405 north, then WA-520 east.

From Seattle: Take WA-520 east.

By airplane: Fly to Seattle's airport, take I-405 north, then WA-520 east.

From WA-520 east, take the 148th Ave NE North exit (this is the second 148th Ave NE exit). Turn right (north) onto 148th Ave NE, proceed a few blocks, and turn right onto NE 36th St. Building 99 will be on the left. The address is 14820 NE 36th St, Redmond, WA 98052-5319. Click here for a map.

## Talk titles and abstracts

**Srinivasa Varadhan** (New York University)*Title:* The role of compactness in large deviations.*Abstract:* The estimates obtained in large deviations are basically local estimates. While it is not a problem for lower bounds it is a problem for upper bounds. In the absence of exponential tightness some type of "compactification" of the space is needed. We will look at some examples.

*Bio:* Professor of Mathematics at Courant Institute New York University. Doctoral degree from Indian Statistical Institute (1963), postdoc at Courant Institute (63-66) followed by faculty position there. Member National Academy of Sciences in USA and Fellow of the Royal Society in UK. Awards include Steele Prize of AMS, Birkhoff prize of SIAM-AMS, and the Abel Prize of the Norwegian Academy of Sciences.

**Alexander E Holroyd** (Microsoft Research)*Title:* Finitely dependent coloring*Abstract:* Do local constraints demand global coordination? I'll address a particularly simple formulation of this question: can the vertices of a graph be assigned random colours in a stationary way, so that neighboring colours always differ, but without long-range dependence? The quest to answer this has led to the discovery of a beautiful yet mysterious new stochastic process that seemingly has no right to exist, while overturning the conventional thinking on a fundamental 49-year old question.

(Joint work with Tom Liggett.)

*Bio:* Senior Researcher at Microsoft Research, Redmond. PhD: University of Cambridge (2000). Previous positions: UCLA (1999-2002), UC Berkeley (2002-2003), University of British Columbia (2002-2008). Awards: Rollo Davidson Prize (2004), Andre-Aisenstadt Prize (2007).

**Tim Hulshof** (University of British Columbia)*Title:* Sharp higher order corrections for the critical value of a bootstrap percolation model*Abstract:* Bootstrap Percolation (BP) models are simple cellular automata with a deterministic growth rule and random initial configuration. It is known that (critical) BP models on the lattice undergo a metastable phase transition on a lattice of fixed size, as the density of the initial configuration increases. Holroyd (2004) determined sharp first order asymptotics for the critical value for the canonical nearest-neighbor model in 2D. Surprisingly, this value turned out to be very far removed from computer simulations of BP on large lattices, suggesting that higher order corrections to the critical value may dominate even on large lattices. We study the scaling of the critical value for the so-called anisotropic (1,2)-model. Duminil-Copin and van Enter recently showed sharp first order asymptotics for the critical value of this model. We determine sharp second and third order corrections, and show that they are both large enough to dominate the critical value of anisotropic bootstrap percolation on any scale that is feasibly accessed by computers.

Based on joint work with Hugo Duminil-Copin, Aernout van Enter, and Robert Morris.

*Bio:* Tim Hulshof received his doctoral degree in 2013 under the supervision of Remco van der Hofstad at the Eindhoven University of Technology, the Netherlands. Currently he is a postdoctoral fellow at UBC and PIMS in Vancouver.

**Benjamin Young** (University of Oregon)*Title:* Sampling from the Fomin-Kirillov distribution*Abstract:* I will describe recent joint work with Sara Billey (UW) and Alexander Holroyd (MSR), generalizing earlier work of mine, in which we bijectively prove the general case of Macdonald's identity in Schubert calculus. As a consequence, we also get a sampling algorithm for a probability distribution on reduced words which is implicit in work of Fomin and Kirillov. The proof involves several novel uses of David Little's generalized "bumping" algorithm.

*Bio:* BY received his PhD under Jim Bryan and Richard Kenyon at UBC in 2008. After postdocs at McGill, MSRI, KTH and MSRI again, he became assistant professor at the University of Oregon in 2012. He works in combinatorics, particularly in areas which are close to algebraic geometry, probability, representation theory and statistical mechanics.

**Ioana Dumitriu** (University of Washington)*Title:* A Regular Stochastic Block Model*Abstract:* The famous Stochastic Block Model (SBM) has been recently completely solved independently by Massoulie and Mossel-Neeman-Sly. Inspired by their work, we have decided to examine a regular variant of the graph; the restrictive nature of the constraints makes the problem easier, but at the same time more challenging (given that we can push the thresholds lower, how much lower can we push them?) This is joint work with Gerandy Brito, Shirshendu Ganguly, Chris Hoffman, and Linh Tran.

*Bio:* Ioana is an Associate Professor in the Math Department at University of Washington. She received her PhD at MIT in 2003, working with Alan Edelman; after that, she was a Miller Fellow at UC Berkeley until 2006, before happily landing in the Great Pacific NW. She is the proud collector of mathematical labels, all of which are great, and none of which quite fits: "numerical analyst," "combinatorialist," "linear algebrist," to which she is now very glad to add "probabilist."

## Hotels

Some nearby hotels include

- Extended Stay America (probably the best choice)

15805 NE 28th Street

Bellevue, WA 98008

(425) 885-6675 - Silver Cloud Inn

10621 NE 12th Street

Bellevue, WA 98004

(800) 205-6937 - Courtyard Marriott (extremely close)

14615 NE 29th Place

Bellevue, WA 98007

(425) 869-5300 - Fairfield Inn Marriott (extremely close)

14595 NE 29th Place

Bellevue, WA 98007

(425) 869-6548 - Residence Inn Marriott-Redmond

7575 164th Ave NE

Redmond, WA 98052

(425) 497-9226 - Silver Cloud Inn (near the University of Washington in Seattle)

5036 25th Avenue NE

Seattle, WA 98105

(800) 205-6940 - University Inn (near the University of Washington)

4140 Roosevelt Way NE

Seattle, WA 98105

(800) 733-3855 - Watertown (near the University of Washington)

4242 Roosevelt Way NE

Seattle, WA 98105

(866) 944-4242