Seminars and Colloquiums
for the week of February 25, 2008
Speakers:
Professor Xiaowen Zhou, Monday
Dr. Jonathan Dursi, Tuesday
Professor Remus Nicoara, Wednesday
Professor David Anderson, Wednesday
Dr. Arthur T. Benjamin, Friday
Monday, February 25
PROBABILITY SEMINAR
TIME: 10:10 – 11:00 a.m.
ROOM: Ayres 309A
SPEAKER: Professor Xiaowen Zhou, Concordia University, Canada
TITLE: “The exit problem for a spectrally negative Levy process partially reflected from its maximum”
ABSTRACT: Let $X$ be a L\'evy process with only negative jumps and $S$ be its running maximum process. For any constant $0<\gamma<1$, define \[Y_t=X_t-\gamma S_t.\] For $-a<0<b $ let \[\tau^+_b=\inf\{t: Y_t>b\}\] and \[\tau^-_{-a}=\inf\{t: Y_t<-a\}.\] In this talk we are going to find an expression for $E\left[e^{-\lambda \tau^+_b}, \tau^+_b<\tau^-_{-a}\right]$. This result is from a recent joint work with Hansjorg Albrecher and Jean-Francois Renaud.
Tuesday, February 26
COLLOQUIUM
TIME: 2:00 p.m.
ROOM: Ayres 125
SPEAKER: Jonathan Dursi, University of Toronto
TITLE: “Instabilities at Astrophysical Fluid Interfaces: Flames, Winds, and Magnetic Fields”
ABSTRACT: Problems of mixing between two fluids comes up in many astrophysical systems, from the surfaces of stars to that of merging galaxy clusters; this mixing is often mediated by instabilities at the interface between the fluids. These interfacial instabilities can be still more interesting when the interfaces have their own dynamics, such as in the case of flames or detonations. In this talk I discuss recent work on instabilities at astrophysical fluid interfaces in a variety of contexts.
Wednesday, February 27
ANALYSIS SEMINAR
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 209A
SPEAKER: Professor Remus Nicoara
TITLE: “On von Neumann Algebras Arising from 2-Cocycles of Property (T) Groups”
ABSTRACT: We consider von Neumann algebras $L(G,\mu)$ associated to Kazhdan property (T) discrete groups $G$ with scalar 2-cocycles $\mu$. We show that, for fixed $G$, there exists no separable finite von Neumann algebra containing $L(G,\mu_i)$ for uncountably many non-equivalent 2-cocycles $\mu_i$ of $G$. In particular, $L(G,\mu_i)$ are non-isomorphic modulo countable sets. This is joint work with S.Popa and R. Sasyk.
In the first talk we give a brief introduction to property (T) groups, projective representations and group von Neumann algebras.
ALGEBRA SEMINAR
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 309A
SPEAKER: Professor David Anderson
Professor Anderson will continue talking about ultrafilters and ultraproducts in commutative ring theory.
Friday, February 29
JUNIOR COLLOQUIUM
TIME: 3:35 p.m.
ROOM: Ayres 214
SPEAKER: Dr. Arthur T. Benjamin
TITLE: “Combinatorial Trigonometry”
ABSTRACT: Many trigonometric identities, including the Pythagorean theorem, have combinatorial proofs. Furthermore, some combinatorial problems have trigonometric solutions. All of these problems can be reduced to alternating sums, and are attacked by a technique we call D.I.E. (Description, Involution, Exception). This technique offers new insights to identities involving binomial coefficients, Fibonacci numbers, derangements, zig-zag permutations, and Chebyshev polynomials.
Interested in giving or arranging a talk? Check out our calendar.
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Seminars from 2006-2007 academic year