[grads] [Sem-coll] Correction to Monday, Nov 13 Joint colloquium

Snejana Abarji snejana at math.iit.edu
Mon Nov 13 11:20:29 CST 2006


Dear All

Excuse me, please, I will miss the seminar today: I do not feel good.
My best wishes to the speaker.

Thank you
Snejana

On Sun, 12 Nov 2006, Robert Ellis wrote:

> The AM/BCPS colloquium Monday will start at 3:45, with coffee at 3:35.
> Sorry for the confusion.  The Friday seminar talk is listed correctly.
>
> ------------------------------------------------------------
> AM/BCPS Colloquium: Monday, Nov 13 ***3:45pm***, LS 111
>
> Speaker: David Fernandez-Baca (Iowa State University )
> Title: Spline Compatibility-Based Clustering of Phylogenetic Data Sets
>
> Abstract:
> The treatment of conflict within data sets is among the most debated
> questions in phylogenetics, and it is an especially relevant concern
> with the accumulation of large data sets that combine data from many
> sources. Indeed, recent genomic-scale phylogenetic analyses have
> called attention to the extent of the variation in the phylogenetic
> signal among loci. This variation results from a several causes,
> including differing relative branch lengths, recombination, and
> horizontal gene transfer. Regardless of its source, identifying
> phylogenetic conflict is an important step in building reliable
> evolutionary trees.
>
> We describe a method to partition phylogenetic data sets of discrete
> characters based on the pairwise compatibility of characters. Unlike
> previous approaches, our method requires no knowledge of the
> phylogeny, model of evolution, or characteristics of the data. The
> method is based on a similarity scoring scheme that measures how close
> pairs of characters are to compatibility. The goal is to partition the
> characters into clusters so that characters within a cluster are more
> compatible with each other than they are with characters in other
> clusters. While partitioning according to these criteria is
> computationally intractable, we show that spectral methods quickly
> provide high-quality solutions. We demonstrate that our partitioning
> method effectively identifies conflicting phylogenetic signals in
> simulated and empirical data sets.
>
> This is joint work with Duhong Chen, of the Department of Computer
> Science, Iowa State University, and J. Gordon Burleigh, of the Section
> of Evolution and Ecology, University of California, Davis.
>
> -----------------------------------------------------------------------
> ----
> AM Seminar: on Friday, Nov 17 3:15pm, E1 119
>
> Speaker: Bridget Tenner (Massachusetts Institute of Technology)
> Title: Reduced Decompositions and Permutation Patterns
>
> Abstract:
> Billey, Jockusch, and Stanley characterized 321-avoiding permutations
> by a property of their reduced decompositions. We generalize that
> result with a study of permutations via their reduced decompositions
> and the notion of pattern containment. These techniques are used to
> prove a new characterization of vexillary permutations in terms of
> their principal dual order ideals in a particular poset. Additionally,
> the combined frameworks yield several new results about the
> commutation classes of a permutation. In particular, these describe
> structural aspects of the corresponding graph of the classes and the
> zonotopal tilings of a polygon defined by Elnitsky that is associated
> with the permutation.
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