Margareta Ackerman Ph.D. Candidate D.R.C. School of Computer Science University of Waterloo mackerma.at.uwaterloo.dot.ca DC2515

I am a PhD candidate working with Professor Shai Ben-David. My main research interest is developing theoretical foundations of clustering that are independent of any specific algorithm or objective function. We provide a consistent set of axioms for clustering, and perform a theoretical study of clusterability (joint work with Ben-David, NIPS '08 and AISTATS '09). Our recent work focuses on providing guidelines for selecting clustering algorithms based on their input-output behaviour (IJCAI '11 with Ben-David, NIPS '10 and COLT '10 with Ben-David and Loker).

Recieved the Outstanding Achievement in Graduate Studies Award for my Master's degree, with the thesis A Theoretical Study of Clusterability and Clustering Quality.

Co-organized a clustering workshop at NIPS '09 with Shai Ben-David, Ulrike von Luxburg, Avrim Blum, Isabelle Guyon, Robert C. Williamson, and Reza Bosagh Zadeh.

My work is supported in part by the Alexander Graham Bell Canada Graduate Scholarship.

Preprints and Working Papers

• Margareta Ackerman and Shai Ben-David. Axioms of Clustering via Quality Measures. (Under journal submission.)
  
  
• Margareta Ackerman and Shai Ben-David. A Characterization of Linkage-Based Hierarchical Clustering. (Under journal submission.)
  
  
• Margareta Ackerman, David Loker, and Alejandro Lopez-Ortiz. Orthogonal Query Expansion. Technical report, CS-2011-23, 2011. arXiv.
  
  
• Margareta Ackerman, Shai Ben-David, Simina Branzei, and David Loker. Weighted Clustering. arXiv.
  
  
• Margareta Ackerman, Shai Ben-David, David Loker, and Sivan Sabato. Polarity of Clustering Algorithms on Dense Regions.
  
  
• Margareta Ackerman, Dan Brown, and David Loker. Re-examining the Effects of Outgroups on Ingroup Topology for Phylogenetic Algorithms, 2011.
  
  
• Joshua Lewis, M. Ackerman, and Virginia De Sa. Human Cluster Evaluation and Formal Quality Measures: A Comparative Study.
  
  
• Margareta Ackerman. Reductions of Graph Isomorphism Problems. Technical Report, CS-2008-08, 2008.

• Margareta Ackerman and Shai Ben-David. Discerning Linkage-Based Algorithms Among Hierarchical Clustering Methods. International Joint Conference on Artificial Intelligence (IJCAI 2011). (Presentation acceptance rate: 17%). [slides]
  
  
• Margareta Ackerman, Shai Ben-David, and David Loker. Towards Property-Based Classification of Clustering Paradigms. Neural Information Processing Systems Conference (NIPS 2010). [Appendix]
  
  
• Margareta Ackerman, Shai Ben-David, and David Loker. Characterization of Linkage-Based Clustering. 23rd International Conference on Learning Theory (COLT 2010). [slides]
  
  
• Margareta Ackerman and Shai Ben-David. Clusterability: A Theoretical Study. Proceedings of the Twelfth International Conference on Artificial Intelligence and Statistics (AISTATS 2009), JMLR: W&CP 5, pp. 1-8. (Presentation acceptance rate: 10%). [slides]
  
  
• Margareta Ackerman and Erkki Makinen. Three New Algorithms for Regular Language Enumeration, Computing and Combinatorics: 15th Annual International Conference (COCOON) , Lecture Notes in Computer Science 5609, Springer-Verlag, Berlin Heidelberg, pp. 178-191, 2009. [slides]
  
  
• Margareta Ackerman and Jeffrey Shallit. Efficient Enumeration of Words in Regular Languages. Theoretical Computer Science (2009) V. 410 (37), Elsevier, pp. 3461-3470.
  
  
• Margareta Ackerman and Shai Ben-David. Measures of Clustering Quality: A Working Set of Axioms for Clustering. Neural Information Processing Systems Conference (NIPS 2008)
  (full oral presentation, acceptance rate: 2.7%) [slides]
  
  
• Margareta Ackerman and Jeffrey Shallit. Efficient Enumeration of Regular Languages. Conference on Implementation and Application of Automata (CIAA) , Lecture Notes in Computer Science, 4783, Springer-Verlag, Berlin Heidelberg, pp. 226-241, 2007. [slides]
  
  
• Daniel Maoz and Margareta Ackerman, "Chavruta and Transformative Learning: A Comparative Analysis," in Opportunities and New Directions: Canadian Scholarship of Teaching and Learning (Edited by N. Simmons. Waterloo: CTE, 2010) pp. 51-59.
  
  
• Daniel Maoz and Margareta Ackerman. "Chavruta: A Novel Teaching Methodology Based on an Ancient Tradition." From Antiquity to the Post-Modern World: Contemporary Jewish Studies in Canada. Newcastle upon Tyne: Cambridge Scholars Publishing, 193-205, 2011

Workshops

• Margareta Ackerman. Towards Theoretical Foundations of Clustering. Grace Hopper Conference (GHC), 2011.
  
  
• Margareta Ackerman, Shai Ben-David, and David Loker. Characterization of Linkage-Based Clustering. NIPS workshop ``Clustering: Science or Art? Towards Principled Approaches.'', 2009.

Invited Talks

• On Theoretical Foundations of Clustering. University of California, Berkeley, 2011.
  
  
• Characterization of Linkage-Based Algorithms. University of California, San Diego, 2010.

Conference Talks

• Discerning Linkage-Based Algorithms Among Hierarchical Clustering Methods. Joint work with Shai Ben-David. IJCAI 2011. Barcelona, Spain.
  
  
• On Theoretical Foundations of Clustering. GHC 2011. Orlando, OR.
  
  
• Characterization of Linkage-Based Clustering. Joint work with Shai Ben-David and David Loker. COLT 2010. Haifa, Israel.
  
  
• Clusterability: A Theoretical Study. Joint work with Shai Ben-David. AISTATS 2009. Clearwater Beach, Florida.
  
  
• Three New Algorithms for Regular Language Enumeration. Joint work with Erkki Makinen. COCOON 2009. Niagra Falls, New York.
  
  
• Measures of Clustering Quality: A Working Set of Axioms for Clustering. Joint work with Shai Ben-David. NIPS, 2008. Vancouver, Canada.
  
  
• Efficient Enumeration of Regular Languages. Joint work with Jeffrey Shallit. CIAA, 2007. Prague, Czech Republic.

Journal/Conference Referee

• Neural Information Processing Systems (NIPS), 2010.
  
• IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI).
  
• The Journal of Pattern Recognition.