Research

Publications

Communication Optimal Parallel Multiplication of Sparse Random Matrices. Grey Ballard, Aydin Buluc, James Demmel, Laura Grigori, Benjamin Lipshitz, Oded Schwartz and Sivan Toledo. To appear in Proceedings of the 25th Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 2013.
- Available as UC Berkeley Tech Report EECS-2013-13.
Communication Efficient Gaussian Elimination with Partial Pivoting using a Shape Morphing Data Layout. Grey Ballard, James Demmel, Benjamin Lipshitz, Oded Schwartz and Sivan Toledo. To appear in Proceedings of the 25th Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 2013.
- Available as UC Berkeley Tech Report EECS-2013-12.
Implementing a Blocked Aasen's Algorithm with a Dynamic Scheduler on Multicore Architectures. Grey Ballard, Dulceneia Becker, James Demmel, Jack Dongarra, Alex Druinsky, Inon Peled, Oded Schwartz, Sivan Toledo, and Ichitaro Yamazaki. To appear in Proceedings of the 27th IEEE International Parallel and Distributed Processing Symposium (IPDPS). 2013. (pdf)
- Received Best Paper award in Algorithms track.
Graph Expansion and Communication Costs of Fast Matrix Multiplication. Grey Ballard, James Demmel, Olga Holtz, and Oded Schwartz. Journal of the ACM. (pdf, bibtex).
- Conference version published in Proceedings of the 23rd Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 2011. (pdf, bibtex).
  - Received Best Paper award.
- Also available as UC Berkeley Tech Report EECS-2011-40.
Communication-Avoiding Parallel Strassen: Implementation and Performance. Benjamin Lipshitz, Grey Ballard, Oded Schwartz, James Demmel. Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis (SC), 2012. (pdf, bibtex)
- Available as UC Berkeley Tech Report EECS-2012-90.
Brief Announcement: Communication Bounds for Heterogeneous Architectures. Grey Ballard, James Demmel, and Andrew Gearhart. Proceedings of the 23rd Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 2011. (pdf, bibtex)
- Extended version, original version available as UC Berkeley Tech Report EECS-2011-13.
Communication-Optimal Parallel Algorithm for Strassen's Matrix Multiplication. Grey Ballard, James Demmel, Olga Holtz, Benjamin Lipshitz, Oded Schwartz. Proceedings of the 24th Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 2012. (pdf, bibtex)
- Available as UC Berkeley Tech Report EECS-2012-32.
Brief Announcement: Strong Scaling of Matrix Multiplication Algorithms and Memory-Independent Communication Lower Bounds. Grey Ballard, James Demmel, Olga Holtz, Benjamin Lipshitz, Oded Schwartz. Proceedings of the 24th Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 2012. (pdf, bibtex)
- Available as UC Berkeley Tech Report EECS-2012-31.
Graph Expansion Analysis for Communication Costs of Fast Rectangular Matrix Multiplication. Grey Ballard, James Demmel, Olga Holtz, Benjamin Lipshitz, Oded Schwartz. Proceedings of Mediterranean Conference on Algorithms, 2012. (pdf, bibtex)
- Available as UC Berkeley Tech Report EECS-2012-30.
Communication Avoiding Successive Band Reduction. Grey Ballard, James Demmel, Nicholas Knight. Proceedings of the 17th ACM Symposium on Principles and Practice of Parallel Programming (PPoPP), 2012. (pdf, bibtex)
Minimizing Communication in Linear Algebra. Grey Ballard, James Demmel, Olga Holtz, and Oded Schwartz. SIAM Journal on Matrix Analysis and Applications, Volume 32, Issue 3, pp 866-901 (2011). (pdf, bibtex)
- Received SIAM SIAG/Linear Algebra Prize.
Communication-Avoiding QR Decomposition for GPUs. Michael Anderson, Grey Ballard, James Demmel, and Kurt Keutzer. Proceedings of the 25th IEEE International Parallel and Distributed Processing Symposium (IPDPS). 2011. (pdf, bibtex)
- Available as UC Berkeley Tech Report EECS-2010-131.
Efficiently Computing Tensor Eigenvalues on a GPU. Grey Ballard, Tamara Kolda, and Todd Plantenga. Proceedings of the 2011 IEEE International Parallel and Distributed Processing Symposium Workshops and PhD Forum (IPDPSW). (pdf, bibtex)
- Available in Sandia National Labs CSRI Summer Proceedings 2010.
Communication-optimal parallel and sequential Cholesky decomposition. Grey Ballard, James Demmel, Olga Holtz, and Oded Schwartz. SIAM Journal on Scientific Computing. Volume 32, Issue 6, pp. 3495-3523 (2010). (pdf, bibtex)
- Conference version published in Proceedings of the 21st Annual ACM Symposium on Parallelism in Algorithms and Architectures (SPAA). 2009. (pdf, bibtex)
Minimizing Communication for Eigenproblems and the Singular Value Decomposition. Grey Ballard, James Demmel, Ioana Dumitriu. (pdf)
- Available as UC Berkeley Tech Report EECS-2011-14.
Existence of Solutions for a Class of Singular Nonlinear Third Order Autonomous Boundary Value Problems. Grey Ballard and John Baxley. Communications in Applied Analysis. Volume 15, No. 2-4, pg. 195-202. 2011. (pdf)
The Friedrichs extension of certain singular differential operators, II. Grey Ballard and John Baxley. Electronic Journal of Qualitative Theory of Differential Equations. Special Edition I, No. 5, pg. 1-11. 2009. (pdf)
Asymptotic behavior of the eigenvalues of Toeplitz integral operators associated with the Hankel transform. Grey Ballard. MA Thesis, Wake Forest University. May 2008. (pdf)
Qualitative behavior and computation of multiple solutions of singular nonlinear boundary value problems. Grey Ballard and John Baxley. Involve, a Journal of Mathematics. Vol. 1, No. 1, pg. 21-31. 2008. (pdf)
Modeling protein dependency networks using CoCoA. Grey Ballard. ACM Crossroads. Issue 13.1. 2006. (pdf)
Qualitative behavior and computation of multiple solutions of nonlinear boundary value problems. Grey Ballard, John Baxley, and Nisrine Libbus. Communications on Pure and Applied Analysis. Vol. 5, No. 2, pg. 251-259. June 2006. (pdf)

Conference and seminar talks

"Avoiding Communication in Dense Linear Algebra." Dissertation talk presented at UC Berkeley in April 2013 in Berkeley, CA. (pdf)
"Avoiding Communication in Parallel Bidiagonalization of Band Matrices." Presented at SIAM Conference on Computational Science and Engineering in March 2013 in Boston, MA. (pdf)
"Communication-Optimal Parallel Algorithm for Strassen's Matrix Multiplication." Presented at Sandia National Labs in August 2012 in Livermore, CA. (pdf)
"Communication-Avoiding Nonsymmetric Eigensolver using Spectral Divide & Conquer." Presented at SIAM Conference on Parallel Processing for Scientific Computing in February 2012 in Savannah, GA. (pdf)
- Updated version presented at IWASEP 9 in June 2012 in Napa, CA. (pdf)
"Lower Bounds for Communication in Linear Algebra." Presented at Workshop on Synchronization-reducing and Communication-reducing Algorithms and Programming Models for Large-scale Simulations in January 2012 in Providence, RI. (pdf)
"Communication-Avoiding Successive Band Reduction." Presented at Householder Symposium XVIII on Numerical Linear Algebra in June 2011 in Tahoe City, CA. (pdf, zip with movies)
- Updated version presented at PPoPP in February 2012 in New Orleans, LA. (pdf, zip with movies)
"Graph Expansion and Communication Costs of Fast Matrix Multiplication." Presented at SPAA in June 2011 in San Jose, CA. (ppt)
"Communication Bounds for Heterogeneous Architectures." Presented at SPAA in June 2011 in San Jose, CA. (pdf)
"Efficiently Computing Tensor Eigenvalues on a GPU." Presented at IEEE International Workshop on Parallel and Distributed Scientific and Engineering Computing (PDSEC) in conjunction with IPDPS in May 2011 in Anchorage, AK. (pdf)
"Communication-Avoiding Dense Linear Algebra." Presented at CScaDS Autotuning Workshop in August 2010 in Snowbird, UT. (pdf)
"GPU Computing for Tensor Eigenvalues." Presented at Sandia National Labs Student Intern Symposium in August 2010 in Livermore, CA. (pdf)
"Mapping Communication-Avoiding QR Decomposition to Various Architectures." Presented at SIAM Annual Meeting in July 2010 in Pittsburgh, PA. (pdf)
"Communication Bounds for Sequential and Parallel Eigenvalue Problems." Presented at SIAM Conference on Parallel Processing for Scientific Computing in February 2010 in Seattle, WA. (pdf)
- Updated version presented at AMS Western Section Meeting and at Sandia National Labs in April 2010 in Albuquerque, NM. (pdf)
"Communication-Optimal Parallel and Sequential Eig/SVD Algorithms." Presented at UC Berkeley LAPACK/Matrix Computations Seminar in December 2009. (pdf)
"Minimizing Communication in Linear Algebra." Presented at SIAM Workshop on Combinatorial and Scientific Computing in October 2009 in Monterey, CA. (ppt)
"Communication-Optimal Parallel and Sequential Cholesky Decomposition." Presented at SPAA in August 2009 in Calgary, Canada. (pdf)
"Minimizing Communication in Linear Algebra." Presented at the Par Lab Summer Retreat in June 2009 in Santa Cruz, CA. (pdf)

Posters

"Communication-Avoiding Parallel Strassen: Implementation and Performance." Presented at the Par Lab Summer Retreat in June 2012. (pdf)
"Communication-Optimal Parallel Algorithm for Strassen's Matrix Multiplication." Presented at the Par Lab Winter Retreat in January 2012. (pdf)
"Communication-Avoiding Successive Band Reduction." Presented at the Par Lab Summer Retreat in June 2011. (pdf)
"Communication Bounds for Heterogeneous Architectures." Presented at SIAM Conference on Computational Science and Engineering in March 2011. (pdf)
"Communication-Optimal Eigenvalue/SVD Algorithms." Presented at the Par Lab Winter Retreat in January 2010. (pdf)
"Minimizing Communication in Linear Algebra." Presented at the Par Lab Summer Retreat in June 2009. (pdf)
"Communication-Optimal Algorithms." Presented at the Bay Area Scientific Computing Day in May 2009. (pdf)
"Communication-Optimal One-Sided Matrix Factorizations." Presented at the Par Lab Grand Opening in December 2008. (pdf)

Last updated 9 February 2013.