Date
Friday December 10, 2021Location
Online via ZoomFriday, December 10th, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Benjamin Hersey (Queen's University)
Title: Intro To Matroids II.
Abstract: We continue to examine the connection between matroids and hyperplane arrangements.
Date
Friday December 3, 2021Location
Online via ZoomFriday, December 3rd, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Benjamin Hersey (Queen's University)
Title: Intro To Matroids.
Abstract: We will define matroids and begin to examine their connection to hyperplane arrangements.
Date
Friday November 26, 2021Location
Online via ZoomFriday, November 26th, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Sonja Ruzic (Queen's University)
Title: On the number of regions.
Abstract: I will prove a theorem of Zaslavsky relating the number of regions of an arrangement A with its characteristic polynomial. I will also define a face of an arrangement and relate that to the number of regions of the arrangement.
Date
Friday November 19, 2021Location
Online via ZoomFriday, November 19th, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Deepanshu Prasad (Queen's University)
Title: Cross-Cut Theorem and Whitney's Theorem.
Abstract: I will prove the Cross-Cut Theorem and Whitney's Theorem and give some examples.
Date
Friday November 12, 2021Location
Online via ZoomFriday, November 12th, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Alexandre (Sasha) Zotine (Queen's University)
Title: Characteristic Polynomial of Arrangements.
Abstract: In this talk, we'll define the characteristic polynomial, which encodes several interesting invariants of an arrangement in one nice algebraic package. To compute characteristic polynomials, we'll introduce two tools: the Deletion/Restriction property, and Whitney's Theorem.
Date
Friday November 5, 2021Location
Online via ZoomFriday, November 5th, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Sonja Ruzic (Queen's University)
Title: Characteristic Polynomials and Projectivization.
Abstract: In this talk, I will continue last week’s discussion of the Möbius function and characteristic polynomial. I will also introduce the projectivization of a linear arrangement and give some examples.
Date
Friday October 29, 2021Location
Online via ZoomFriday, October 29th, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Deepanshu Prasad (Queen's University)
Title: Intersection Posets and Characteristic Polynomials.
Abstract: I will be talking about the Intersection Posets, Mobius Function of a Poset and the Characeristic Polynomial of an Arrangement. If time permits, then I will also discuss the Projectivization of a Linear Arrangement.
Date
Friday October 22, 2021Location
Online via ZoomFriday, October 22nd, 2021
Time: 12:00 p.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Alexandre (Sasha) Zotine (Queen's University)
Title: An Introduction to Hyperplane Arrangements.
Abstract: In this talk, I will give introduce hyperplane arrangements, and some basic defining properties associated with them. We will look at several examples, including the Braid arrangement, which is likely to reappear often.
Date
Monday February 7, 2022Location
Online via ZoomMonday, February 7th, 2022
Time: 11:00 a.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Deepanshu Prasad (Queen's University)
Title: Coxeter arrangements and Shi arrangements.
Abstract: We will look at the Coxeter arrangements, arising from root systems, and Shi arrangements. We will calculate their characteristic polynomial using the finite field method and talk about their "supersolvability" and "freeness".
Date
Monday January 31, 2022Location
Online via ZoomMonday, January 31st, 2022
Time: 11:00 a.m. Place: Online via Zoom (contact Deepanshu Prasad for Zoom link)
Speaker: Alexandre (Sasha) Zotine (Queen's University)
Title: Graphical Arrangements cont.
Abstract: We will finish our discussion of graphical arrangements by covering orientations of graphs and relating them to the regions of their associated arrangements. Once this is finished, I will start to introduce some finite field methods for computing characteristic polynomials over the rationals.
