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'''John''': [http://www.siam.org/proceedings/soda/2010/SODA10_065_ericksonj.pdf Maximum Flows and Parametric Shortest Paths in Planar Graphs] ''Jeff Erickson''
'''John''': [http://www.siam.org/proceedings/soda/2010/SODA10_065_ericksonj.pdf Maximum Flows and Parametric Shortest Paths in Planar Graphs] ''Jeff Erickson''
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Abstract:
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''We observe that the classical maximum flow problem in any directed planar graph G can be reformulated as a parametric shortest path problem in the oriented dual graph G�. This reformulation immediately suggests an algorithm to compute maximum flows, which runs in O(n log n) time. As we continuously increase the parameter, each change in the shortest path tree can be effected in O(log n) time using standard dynamic tree data structures, and the special structure of the parametrization implies that each directed edge enters the evolving shortest path tree at most once. The resulting maximum-flow algorithm is identical to the recent algorithm of Borradaile and Klein [J. ACM 2009], but our new formulation allows a simpler presentation and analysis. On the other hand, we demonstrate that for a similarly structured parametric shortest path problem on the torus, the shortest path tree can change (n2) times in the worst case, suggesting that a different method may be required to efficiently compute maximum flows in higher-genus graphs.''
This is a paper from SODA '10 that I thought was particularly interesting. It takes an older result and casts it in a topological setting.
This is a paper from SODA '10 that I thought was particularly interesting. It takes an older result and casts it in a topological setting.

Revision as of 21:32, 3 February 2010

The Algorithms For Lunch Bunch

Thursdays at 12:30.

Contents

Spring 2010

Jan 8, 2010

Jan14, 2010

Jeff: Combinatorial view of Markov chain Monte Carlo.

Jan 21, 2010

SODA recaps Part I: Parasaran and Jeff

Parasaran

Jeff

Jan 28, 2010

SODA recaps Part II

Suresh (Poincare inequalities):

John:

Feb 4, 2010

John: Maximum Flows and Parametric Shortest Paths in Planar Graphs Jeff Erickson

Abstract: We observe that the classical maximum flow problem in any directed planar graph G can be reformulated as a parametric shortest path problem in the oriented dual graph G�. This reformulation immediately suggests an algorithm to compute maximum flows, which runs in O(n log n) time. As we continuously increase the parameter, each change in the shortest path tree can be effected in O(log n) time using standard dynamic tree data structures, and the special structure of the parametrization implies that each directed edge enters the evolving shortest path tree at most once. The resulting maximum-flow algorithm is identical to the recent algorithm of Borradaile and Klein [J. ACM 2009], but our new formulation allows a simpler presentation and analysis. On the other hand, we demonstrate that for a similarly structured parametric shortest path problem on the torus, the shortest path tree can change (n2) times in the worst case, suggesting that a different method may be required to efficiently compute maximum flows in higher-genus graphs.

This is a paper from SODA '10 that I thought was particularly interesting. It takes an older result and casts it in a topological setting.

Feb 11, 2010

Arvind: Generalized MDS.

Fall 2009

Oct 30, 2009

All: Discussion of topics for Spring 2010 Algorithms Seminar on Graph Algorithms

  • planarity testing
  • advanced MSTs ? randomized MST
  • other randomized graph algorithms
  • treewidth/pathwidth
  • minors
  • robertson seymour (in brief)
  • Baker decomposition for planar graphs
  • Klein-Borradaile results on new decompositions
  • shortest paths, matrix mult, new developments
  • evasiveness in graph properties, and the topological angle
  • Spectral graph theory?

Nov 7, 2009

  • John, Raj: Practice talks for FWCG 09
  • Parasaran: Geometry of Soft Clusterings

Nov 14, 2009

No AFLB (FWCG 2009)

Nov 21, 2009

Review of FWCG papers:

  • Wei Zeng, Rik Sarkar, Feng Luo, Xianfeng Gu, and Jie Gao. Resilient Routing for Sensor Networks Using Hyperbolic Embedding of Universal Covering Space
  • Gary L. Miller, Todd Phillips, and Donald R. Sheehy. Approximating Voronoi Diagrams with Voronoi Diagrams

(2 page abstracts here)

Dec 4, 2009

Papers for discussion

Contact

If you are interested in giving a talk at AFLB or have questions, please feel free to send a mail to moeller@cs.utah.edu, praman@cs.utah.edu or avishek@cs.utah.edu. If you are planning to give a talk, we would really appreciate if you have an abstract ready a week before the talk is scheduled.

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