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Andres Caicedo
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Andres Caicedo

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Elisenda Grigsby is the inaugural recipient of the AWM-Joan and Joseph Birman Research Prize in Topology and Geometry.
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Andres Caicedo

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QR method and eigenvalues

to illustrate the course of numerical analysis I currently give to my students, and I made (using scilab software) short animations like the gif below . The magnitude of matrix coefficients is represented by a color (black/deep blue for low values, red/white for hight ones) For a symmetric matrix the process tends quickly  to a diagonal matrix with values sorted in decreasing order on its diagonal which are the eigenvalues of A . The method also works for non-symmetric matrix but the process converge to a upper-triangular matrix , you can see it in my previous gif :

https://plus.google.com/+philipperoux/posts/cuXqSgp4CuA


#mathematics      #eigenvalue #matrix #scilab  

See also :
http://en.wikipedia.org/wiki/QR_algorithm
http://en.wikipedia.org/wiki/QR_decomposition
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Diophantine Equations

Tuesday, September 15, 2015 to Saturday, September 19, 2015

LMS-CMI Research School

Baskerville Hall
Hay-on-Wye, UK

Organizers: Tim Dokchitser (Bristol), Vladimir Dokchitser (Warwick)

The course will give an overview of the existing methods for investigating integer and rational solutions to Diophantine equations. It will include both the algebraic, analytic and model theory aspects of the subject. The course will take the format of three 6-hour mini-courses, supported by exercise classes.

1. Rational Points
A. Rational points on curves (Michael Stoll, Bremen)
B. Higher-dimensional varieties (Alexei Skorobogatov, Imperial)

2. Integral Points
A. Basic methods and solubility (Jennifer Park, McGill)
B. Analytic methods, (Trevor Wooley, Bristol)

3. Elliptic and modular curves
A. Elliptic curves (Tim Dokchitser, Bristol and Vladimir Dokchitser, Warwick)
B. Modularity (Andrew Granville, Montreal/UCL)
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(Via Noah Schweber on the FOM list)

First Announcement
2nd Workshop on Vaught's Conjecture
June 1-5, 2015 at the University of California - Berkeley
https://math.berkeley.edu/~schweber/vcc15/

Organized by:
 - Julia Knight (University of Notre Dame, Julia.F.Knight.1@nd.edu)
 - Antonio Montalbán (UC Berkeley, antonio@math.berkeley.edu)
 - Thomas Scanlon (UC Berkeley, scanlon@math.berkeley.edu)
 - Noah Schweber (UC Berkeley, schweber@math.berkeley.edu)

******

A workshop on the mathematics surrounding Vaught's Conjecture (on the number of isomorphism types of countable models of a countable complete first order theory) will be held at the University of California at Berkeley from June 1 to June 6, 2015. The first workshop on Vaught's Conjecture was held at the University of Notre Dame, in May of 2005. This workshop resulted in a number of new ideas and collaborations, some of which were published in a special issue of the Notre Dame Journal of Formal Logic. We hope that this second workshop will build on the success of the first. 


There will be tutorials by Uri Andrews, Su Gao, and Chris Laskowski; the invited speakers currently include:

Nate Ackerman
John Baldwin
Howard Becker
Samuel Coskey
Cameron Freer
Sy Friedman
Robin Knight
Paul Larson
David Marker
Ludomir Newelski
Richard Rast
Gerald Sacks
Slawomir Solecki
Ioannis Souldatos
A workshop on Vaught's Conjecture will be held at the University of California - Berkeley on June 1-5 of 2015, with support from the David and Lucile Packard Foundation. Organizers Julia Knight (Julia.F.Knight.1@nd.edu), Antonio Montalbán (antonio@math.uchicago.edu), Thomas Scanlon ...
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I hope they figure it out!
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Jíři Matoušek died earlier this week, after a long illness.  Jirka was an inspirational researcher in discrete and computational geometry and topology, with seminal results on many different topics, including geometric range searching, discrepancy theory, derandomization, linear programming, metric embeddings, and algorithmic topology. He was also the author of several beautifully written textbooks and monographs.

János Pach reports that Jirka continued to work on his newest book through the last day of his life.

He will be sorely missed.
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2015 BOISE EXTRAVAGANZA IN SET THEORY (BEST) - ANNOUNCEMENT 1.

http://diamond.boisestate.edu/~best/
DATE:     June 15 - 17, 2015
WHERE: San Francisco State University

The 22-nd annual meeting of BEST will be hosted at San Francisco State University as a symposium of the 96th annual meeting of the American Association for the Advancement of Science - Pacific Division (AAAS-PD).
Contributed and invited talks at BEST will be held on Monday, Tuesday and Wednesday.

In addition to invited speakers, the conference program has reserved speaking slots for students, post docs and pre-tenure tenure track faculty. NSF supported funding to assist up to ten student speakers, four post-doc speakers and two pre-tenure tenure track faculty speakers is available. For details on applying to the BEST program committee for these, please visit the conference website at the URL provided above. In addition, the AAAS-PD provides up to $150 in travel funding for students. Please see the BEST conference website for more details on these also. There are a number of deadlines associated with applications for a travel grant.

Currently confirmed plenary speakers for BEST 2015 are:

Dr. Rodrigo Dias, University of Sao Paulo, Brazil
Dr. Mirna Dzamonja, East Anglia University, U.K.
Dr. Aleksandra Kwiatkowska, UCLA
Dr. Spencer Unger, UCLA
Dr. Trevor Wilson, Miami University, OH

Special features of BEST 2015 include:

In addition to the BEST symposium there are several other symposia and workshops of interest offered at the AAAS-PD annual meeting. On Monday, June 15, the AAAS-PD organized an evening at the California Academy of Sciences on Tuesday, June 16, the AAAS-PD hosts a banquet at which awards of excellence are given to student speakers selected by a panel of judges.

Student, post-doc and pre-tenure tenure track speakers are strongly
encouraged to apply to BEST for an NSF-funded travel award. The travel expenses (airfare and lodging) of awarded speakers will be reimbursed up to the maximum amount of the award, and registration fees of awardees will be reimbursed.

STUDENT SPEAKERS:
===================
BEST seeks to promote student participation in the conference via short (20 minute) presentations. To this end there are ten (10) NSF funded BEST travel awards  available for students. To apply for one of these awards, please follow the instructions given at the BEST website.

In addition to the BEST travel awards, up to 20 travel awards of up to $150 each are also available from the AAAS-PD to help students (including students participating in BEST) defray travel expenses to participate in the AAAS-PD annual meeting. Winners of these AAAS-PD travel awards will be announced at the AAAS-PD student award banquet. Student participants will be guests at this banquet.

POST-DOC and PRE-TENURE TENURE TRACK SPEAKERS:
================================================
BEST also seeks to be a forum for early career set theoretic scholars. In particular there are NSF funded BEST travel awards available for post-docs, and for pre-tenure tenure track faculty. To apply for one of these awards, please follow the instructions given at the BEST website.

CONTRIBUTED TALKS:
===================

The BEST schedule will also have a number of slots for 25 minute contributed talks. Anyone wishing to speak at BEST 2015 should submit an abstract as soon as possible (preferably prior to April 05) at the abstract submission site. It is strongly recommended to also contact one of the organizers as soon as possible to indicate interest/intention in presenting a talk  at BEST 2015.

Important deadlines:

DEADLINE 1: REGISTRATION: Please consult
http://diamond.boisestate.edu/~best/ for registration costs and
deadlines.
Registration fees depend on date of registration. We kindly request that Ph.D. mathematicians planning to participate in BEST 2015
consider acting as judges for the student presentations. The registration form has a place where willingness to act as a judge can be indicated.

There are also a number of excursions available that can be indicated on the registration form. Also consider attending the awards banquet in support of our student speakers - meal choices are available on the registration form.

DEADLINE 2: ABSTRACTS: Atlas Conferences, Inc. is providing abstract services for BEST 2015. Abstracts submitted by April 1 will appear in the proceedings of the annual conference of the AAAS-PD. The url for the abstract submission is available at the BEST 2015 website.

DEADLINE 3: TRAVEL GRANTS: Presenting students, post-docs or pre-tenure tenure track faculty, please complete the application process to BEST by May 15. See the BEST 2015 website for details. Students, the deadline for the AAAS-PD student travel grants is May 1, 5:00 p.m. Pacific time.

Organized by Liljana Babinkostova, Andres E. Caicedo, Sam Coskey, and Marion Scheepers.

For any questions, please contact an organizer or e-mail
best@math.boisestate.edu
We are pleased to announce that BEST 2015 will be held on the campus of. San Francisco State University during June 14 – 17, 2015. The conference is organized as a symposium of the 96th Annual Meeting of the AAAS Pacific Division. The mission of BEST 2015 is to provide a forum for interactions ...
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Born March 1st, at 6:09am. 5 pounds 14.9 ounces. Related.
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¡Felicitaciones!
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Andres Caicedo

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QR method and eigenvalues
I'm currently working on a course of numerical analysis for my students, and I've realized (using scilab software) a short animation to help them understanding how the QR method works . The QR method is a fast algorithm for computing matrix eigenvalues . It is based on the QR decomposition of a matrix A : a factorization A=Q*R where R is upper-triangular and Q is orthogonal. The QR decomposition can be obtained from Gram-Schmidt process applied to column vectors of A. Then the QR method can be implemented in a very simple way :
compute QR decomposition of A
replace A by R*Q
repeat until R be sufficiently
close to a upper-triangular matrix
In the gif below you can visualize the behavior of matrix coefficients : the absolute value of each cell is represented by a color (black/deep blue for low values, red/white for hight ones) and you can see that quickly the matrix tends to be upper-triangular with values sorted in decreasing order on its diagonal which are the eigenvalues of A . The explanation is that at each step of the algorithm , the new matrix A is similar to the old one, because R*Q=Q'*A*Q, so they have the same spectrum which corresponds to diagonal values for a triangular matrix. Note also that  the sequence of Q matrix tends to a diagonal matrix  with +1 or -1 diagonal values, The error value is the norm || Id(i,j) - |Q(i,j)|  ||  is close to the relative error on eigenvalues, and is a good stopping criteria for the algorithm's loop.

#mathematics #eigenvalue #matrix     #scilab

See also :
http://en.wikipedia.org/wiki/QR_algorithm
http://en.wikipedia.org/wiki/QR_decomposition
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I will be taking a leave from BSU this coming academic year, and moving to Ann Arbor, to work as an Associate Editor at MathReviews.
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+Robert Lubarsky  Hi Bob. It should be fine. Reply to one of the automated emails informing you of the lateness, and indicate a realistic deadline now that the term is almost over. They should get back to you in case the new deadline can work. If not, well, these things happen.
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Summer school for graduate students in set theory at UC Irvine (July 6 - 17, 2015).  The theme is forcing and large cardinals, the instructors are Brent Cody (VCU), Monroe Eskew (VCU), and Spencer Unger (UCLA).
 https://gssst2015.wordpress.com/ 

Masters or PhD students with the appropriate background (or their advisors), please contact Sean Cox (details at the link above).  US citizens and permanent residents are fully covered. 
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kinda tempted to go....
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I finally finished LaTeXing Lester Hill's paper (from the 1920s?) when he discovered error-correcting codes (which he called error-detecting codes, since he did not realize when they were). Essentially, he discovered (about 20 years before Hamming and Golay) cyclic MDS codes without knowing it, and never published his notes. 
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The conference in honor of Woodin's 6oth birthday is near the end of the month. 

http://logic.harvard.edu/woodin_meeting.html
Conference Speakers. H. Garth Dales (University of Lancaster); Qi Feng (Chinese Academy of Sciences); Matthew D. Foreman (University of California, Irvine); Ronald Jensen (Humboldt University of Berlin); Alexander S. Kechris (California Insitute of Technology); Menachem Magidor (Hebrew ...
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Mathematician at Boise State University.
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