Department of Mathematics,
University of California San Diego

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Math 269 - Combinatorics

Cheng Yeaw Ku
Math Department, Caltech

Intersecting families of permutations and partial permutations.

Abstract:

A set of permutations on $n$ points is intersecting if, for
any two of its elements, there is some point which is sent to the same
point by both of them. How large can such a set be? Similarly, a set
of partial permutations (meaning injections defined on some $r$ points
of the $n$-set, for some fixed $r$) is intersecting if, for any two of its
elements, there is some point on which they are both defined and is
sent to the same point by both of them. Again, how large can such a
set be?

We shall survey and discuss some results on these problems. We will
also mention some fascinating conjectures in this area.

This talk includes joint work with Peter Cameron and Imre Leader.

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AP&M 7321

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Department of Mathematics,
University of California San Diego

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Differential Geometry/Analysis Seminar

Ovidiu Munteanu
UCI

A sharp estimate for the bottom of the spectrum of the Laplacian on Kaehler manifolds

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AP&M 7218

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Department of Mathematics,
University of California San Diego

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Probability Seminar

Keh-Shin Lii
University of California, Riverside

Modeling marked point processes

Abstract:

New probability models are proposed for the analysis of marked point
processes. These models deal with the type of data that arrive
or are observed in possibly unequal time intervals such as
financial transactions, earthquakes among others. The models
treat both the time between event arrivals and the observed marks
as stochastic processes. We adopt a class of bivariate
distributions to form the bivariate mixture transition
distribution(BMTD). In these models the
conditional bivariate distribution of the next
observation given the past is a mixture of conditional
distributions given each one of the last p observations or a
selection of past p events. The identifiability of the model is
investigated, and EM algorithm is developed to obtain estimates
of the model parameters. Simulation and real data examples are
used to demonstrate the utility of these models.

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AP&M 6402

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Department of Mathematics,
University of California San Diego

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Food for Thought Seminar

Allen Knutson
UCSD

Moduli spaces and quotients by groups: Part ][

Abstract:

Last time I described the (na\"ive) algebraic geometry way to define

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AP&M 7321

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Department of Mathematics,
University of California San Diego

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Math 209 - Number Theory

James Barrett
King's College London

Dirichlet L-functions at strictly positive integers and Fitting invariants of K-groups

Abstract:

For K a C.M. abelian extension of a totally real base-field k with
Galois group G, Solomon has recently constructed for each prime p a Z p[G] ideal of Q p[G] related to values of Dirichlet L-functions at s=1 and conjectured that this ideal is contained within Z p[G]. Jones has subsequently shown that for each odd p the Equivariant Tamagawa Number Conjecture (or ETNC) implies that Solomon's ideal should actually be contained within the Fitting ideal of the class-group of O K. I shall explain how to define analogous ideals related to values of Dirichlet L-functions at integers r strictly greater than 1 and provide a sketch of the techniques used to show that the ETNC relates these `higher Solomon ideals' to the Fitting ideals of certain natural cohomology groups (and thus, when the Quillen-Lichtenbaum conjecture is valid, to Fitting ideals of Quillen K-groups of O K). In particular, for certain choices of K/k and r these results are
unconditional as the relevant cases of the ETNC and Quillen-Lichtenbaum conjecture are known to be valid.

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AP&M 7321

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Department of Mathematics,
University of California San Diego

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Geometry/String Theory Seminar

David R. Morrison
UCSB/KITP

Ricci flow and membrane theory

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AP&M 6402

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Department of Mathematics,
University of California San Diego

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Southern California Algebraic Geometry Seminar

Tom Graber
CalTech

Restriction of sections for families of abelian varieties

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AP&M 6402

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Department of Mathematics,
University of California San Diego

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Southern California Algebraic Geometry Seminar

Bernd Siebert
Freiburg

Tropical geometry and mirror symmetry

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AP&M 6402

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Department of Mathematics,
University of California San Diego

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Southern California Algebraic Geometry Seminar

Paolo Cascini
UCSB

Finite generation of the canonical ring I

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AP&M 6402

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Department of Mathematics,
University of California San Diego

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Southern California Algebraic Geometry Seminar

James McKernan
UCSB

Finite generation of the canonical ring II

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AP&M 6402

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