Judy Walker's Home Page

Contact Info
  Aaron Douglas Professor
Chair, Department of Mathematics
University of Nebraska - Lincoln
Lincoln, NE 68588-0130
E-mail: judy.walker@unl.edu
Office: 206 Avery Hall
Office Phone: (402) 472-3731
Fax: (402) 472-8466
  Click for Lincoln, Nebraska Forecast
My Vita (PDF file)


Current Courses

As Chair, I teach only one course per year. I am looking forward to teaching Math 189H in Fall 2013. The title of this honors freshman seminar is "The Joy of Numbers: Stalking the Big Primes".
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Nebraska Mentoring through Critical Transition Points

The Department of Mathematics at the University of Nebraska has been awarded two 5-year grants titled Nebraska Mentoring through Critical Transition Points by the National Science Foundation. I was the lead PI on the first of these grants and a co-PI on the current one.

Nebraska Conference for Undergraduate Women in Mathematics

The Fifteenth Annual Nebraska Conference for Undergraduate Women in Mathematics was held at UNL January 25-27, 2013. See our website for more information. If you have questions, send email to ncuwm@math.unl.edu.

By the way, this conference was started in celebration of the UNL Department of Mathematics and Statistics receipt of the 1998 Presidential Award for Excellence in Science, Mathematics, and Engineering Mentoring.(Follow that link for information on the award, and to see a cool picture of me with President Clinton!)


Research Interests

Christine Kelley and I organized a Special Session on Coding Theory at the AMS Sectional Meeting in Lincoln on October 14-16, 2011.
I was on leave for the Fall 2011 semester, spending a good chunk of the semester at a special program in Combinatorial, Algebraic and Algorithmic Aspects of Coding Theory at the Bernoulli Institute in Lausanne, Switzerland.

My main research area is algebraic coding theory.
Here are some of my recent papers (sorry; this is in need of updating):

Connections between computation trees and graph covers (coauthor: D. Dreher)
in Proceedings of the 2009 Information Theory and Applications Workshop, San Diego, CA; February 2009.
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Towards universal cover decoding (coauthors: N. Axvig, D. Dreher, K. Morrison, E. Psota and L.C. Pérez)
in Proceedings of the 2008 International Symposium on Information Theory and its Applications, Auckland, New Zealand; December 2008.
PDF file

Average min-sum decoding of LDPC codes (coauthors: N. Axvig, D. Dreher, K. Morrison, E. Psota and L.C. Pérez)
in Proceedings of the 2008 International Symposium on Turbo Codes and Related Topics (TURBO), Laussanne, Switzerland; September 2008.
PDF file

Analysis of connections between pseudocodewords (coauthors: N. Axvig, D. Dreher, K. Morrison, E. Psota and L.C. Pérez)
accepted pending revisions to IEEE Transactions on Information Theory, October 2008.
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A universal theory of decoding and pseudocodewords (coauthors: N. Axvig, D. Dreher, K. Morrison, E. Psota and L.C. Pérez)
SGER Technical report, 2008.
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Algebraic geometric codes over rings (coauthor: K. Bartley)
to appear in Advances in Algebraic Geometry Codes, Series on Coding Theory and Cryptography (World Scientific); E. Martinez-Moro, C. Munuera and D. Ruano, eds.
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LDPC codes from voltage graphs (coauthor: C. Kelley)
to appear in International Symposium on Information Theory (ISIT), July 2008.
PDF file

A universal theory of pseudocodewords (coauthors: N. Axvig, E. Price, E. Psota, D. Turk, L.C. Perez)
In the proceedings of the 45th Annual Allerton Conference on Communication, Control, and Computing
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Characterizations of pseudo-codewords of LDPC codes (coauthors: Ralf Koetter, Winnie Li and Pascal Vontobel)
Advances in Mathematics, 217 (2007) 205-229.
Due to copyright restrictions, I cannot post this paper here. But please email me if you'd like me to send you the .pdf.

Pseudo-codewords of cycle codes via zeta functions (coauthors: Ralf Koetter, Winnie Li and Pascal Vontobel)
in Proceedings of the IEEE Information Theory Workshop, San Antonio, TX, Oct. 24-29, 2004.
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s-extremal additive GF(4) codes (coauthors: E.P. Bautista, P. Gaborit and J.-L. Kim)
Advances in Mathematics of Communications 1 (2007) 111-130.
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Nonbinary quantum error-correcting codes from algebraic curves (coauthor: Jon-Lark Kim)
Discrete Math 308 (2008) 3115-3124.
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Applications of list decoding to tracing traitors (coauthors: Alice Silverberg and Jessica Staddon)
IEEE Transactions on Information Theory, 49 (2003) 1312-1318.
DVI file PDF file

Homogeneous weights and exponential sums (coauthor: Jose Felipe Voloch)
Finite Fields and Their Applications, 9 (2003) 310-321.
DVI file PDF file

Efficient traitor tracing algorithms using list decoding (coauthors: Alice Silverberg and Jessica Staddon)
In Advances in Cryptology - ASIACRYPT 2001, Lecture Notes in Computer Science 2248, 175-192.

A critical look at self-dual codes
In the proceedings of the 38th Annual Allerton Conference on Communication, Control, and Computing
DVI file PDF file

Constructing critical indecomposable codes
IEEE Transactions on Information Theory, 47 (2001) 1780-1795.

Codes and Curves
This is an expository monograph, published by the AMS in the IAS/Park City Mathematical Subseries of the Student Mathematical Series, available from the American Mathematical Society. A corrected reprint will be available from the AMS soon!

Codes over rings from curves of higher genus (coauthor: Jose Felipe Voloch)
IEEE Transactions on Information Theory 45(1999), 1768-1776.

Lee weights of Z/4Z-codes from elliptic curves (coauthor: Jose Felipe Voloch)
in Codes, Curves, and Signals: Common Threads in Communications
DVI file Postscript file

Euclidean weights of codes from elliptic curves over rings (coauthor: Jose Felipe Voloch)
Transactions of the American Mathematical Society, 352 (2000), 5063-5076.

Algebraic geometric codes over rings
J. Pure Appl. Algebra 144 (1999), 91-110.

The Nordstrom-Robinson code is algebraic geometric
IEEE Transactions on Information Theory 43(1997), 1588-1593.

A new approach to the main conjecture on algebraic geometric MDS codes
Designs, Codes and Cryptography 9 (1996), 115-120.

In addition, I have one paper on finite group theory:

Two-groups with few conjugacy classes (coauthor: Nigel Boston )
Proc. Edinburgh Math. Soc. (2) 43 (2000), 211-217.
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Teaching Interests

Project NExT
Project NExT is an MAA program, funded with a grant from the Exxon Educational Foundation, for new and recent Ph.D.'s in their first few years of a teaching position. I am a 1996-7 Project NExT Fellow (a "Blue Dot").
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Cool Links

Someday, they'll even be ORGANIZED cool links!

I got my PhD at the University of Illinois. My advisor was Nigel Boston (now at the University of Wisconsin).

UIUC has the MAGMA handbook online. You can go straight to the index if you want.

Another tool for group theory is GAP. It's free but not as powerful as MAGMA.

If you're more interested in commutative algebra or algebraic geometry, Macaulay 2 is very useful.

I serve on the editorial board for three journals:
    Journal of Pure And Applied Algebra (JPAA)
    Advances in Mathematics of Communications (AMC)
    Rose-Hulman Undergraduate Mathematics Journal

The American Mathematical Society page has lots of useful information for mathematicians, including the Combined Membership List, a list of AMS Meetings and Conferences, and MathSciNet.

The National Security Agency offers grants to people working in certain types of mathematics.

The Penn State Math Department maintains a list of Mathematics Information Servers. You can jump directly to the USA list if you want.

The IEEE is a professional society for electrical engineers. The IEEE Transactions on Information Theory is a journal which publishes lots of great articles on coding theory.

The National Science Foundation also funds all sorts of mathematics- (and science-) related activities. The Division of Mathematical Sciences is the main place to go for grants in mathematics. To apply for a grant, you need the Grant Proposal Guide. You also need to know about Fastlane.

You can find an address or phone number for just about anything at BigBook, or you might want to try AnyWho.

If you need to know currency exchange rates, there's a great site at Yahoo.

Travelocity provides a good search engine for plane tickets and rental cars, as does Expedia.

The best place to check flight status is at Yahoo.

Midwest Express offers nonstop flights from Omaha to many places with "first class" service.

If you want general quotations, Bartlett's can't be beat. However, there's another site for Mathematical Quotations.

Want to see a movie in Lincoln? Maybe you should check out a review first (from Roger Ebert at the Chicago Sun Times).

For driving directions, check out MapQuest.

Check out the online Merriam-Webster Dictionary for all your spelling and definition needs! You can also improve your vocabulary with their Word-of-the-Day page.

Francis Su, a Project NExT Blue Dot at Harvey Mudd, put together a page of Math Fun Facts!
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Judy Walker's Home Page
Last modified: Fri Jun 7 10:31:23 CDT 2013
Comments to jwalker@math.unl.edu