The papers in this volume were presented at the 9th Workshop on Algorithms and Data Structures (WADS 2005). The workshop took place during August 15 17, 2005, at the University of Waterloo, Waterloo, Canada. The workshop alternateswith the ScandinavianWorkshopon Algorithm Theory(SWAT), c- tinuing the traditionof SWAT and WADS startingwith SWAT 1988and WADS 1989. From 90 submissions, the Program Committee selected 37 papers for p- sentation at the workshop. In addition, invited lectures were given by the f- lowing distinguished researchers: Allan Borodin and Max J. Egenhofer. OnbehalfoftheProgramCommittee,wewouldliketoexpressoursincere- preciation to the many persons whose e?ort contributed to making WADS 2005 a success. These include the invited speakers,members of the ste- ing and ProgramCommittees, the authors who submitted papers, and the many referees who assisted the ProgramCommittee. We are indebted to Robert Kane forinstallingandmodifyingthesubmissionsoftware,maintainingthesubmission server and interacting with authors as well as for helping with the preparation of the program. August 2005 Frank Dehne, Alejandro Lop ez-Ortiz, and Jorg-R u diger Sack WADS Organization Organizing Institutions Steering Committee Frank Dehne Carleton University, Canada Ian Munro University of Waterloo, Canada J org-Rudig er Sack Carleton University, Canada Roberto Tamassia Brown University, Canada Program Co-chairs Frank Dehne Carleton University, Canada Alejandro Lop ez-Ortiz University of Waterloo, Canada J org-Rudig er Sack Carleton University, Canada Conference Chair Alejandro Lop ez-Ortiz University of Waterloo, Canada Program Committee Pankaj Agarwal Duke University, USA Michael Atkinson University of Otago, New Zealand Gill Barequet Technion, Israel Mark de Berg Tech.

Inhalt
Session 1.- Towards a Theory of Algorithms.- Session 2A.- k-Restricted Rotation with an Application to Search Tree Rebalancing.- Heap Building Bounds.- Session 2B.- The Multi-radius Cover Problem.- Parameterized Complexity of Generalized Vertex Cover Problems.- The Complexity of Implicit and Space Efficient Priority Queues.- Analysis of a Class of Tries with Adaptive Multi-digit Branching.- Balanced Aspect Ratio Trees Revisited.- Session 3B.- Improved Combinatorial Group Testing for Real-World Problem Sizes.- Parameterized Counting Algorithms for General Graph Covering Problems.- Approximating the Online Set Multicover Problems via Randomized Winnowing.- Session 4A.- Max-stretch Reduction for Tree Spanners.- Succinct Representation of Triangulations with a Boundary.- Line-Segment Intersection Made In-Place.- Session 4B.- Improved Fixed-Parameter Algorithms for Two Feedback Set Problems.- Communication-Aware Processor Allocation for Supercomputers.- Dynamic Hotlinks.- Session 6A.- The Minimum-Area Spanning Tree Problem.- Hinged Dissection of Polypolyhedra.- Session 6B.- Convex Recolorings of Strings and Trees: Definitions, Hardness Results and Algorithms.- Linear Time Algorithms for Generalized Edge Dominating Set Problems.- Session 7A.- On Geometric Dilation and Halving Chords.- Orthogonal Subdivisions with Low Stabbing Numbers.- Kinetic and Dynamic Data Structures for Convex Hulls and Upper Envelopes.- Session 7B.- Approximation Algorithms for Forests Augmentation Ensuring Two Disjoint Paths of Bounded Length.- A Dynamic Implicit Adjacency Labelling Scheme for Line Graphs.- The On-line Asymmetric Traveling Salesman Problem.- Session 8A.- All-Pairs Shortest Paths with Real Weights in O(n 3/log n) Time.- k-Link Shortest Paths in Weighted Subdivisions.- Power-SavingScheduling for Weakly Dynamic Voltage Scaling Devices.- Session 8B.- Improved Approximation Algorithms for Metric Maximum ATSP and Maximum 3-Cycle Cover Problems.- On the Vehicle Routing Problem.- Session 9A.- The Structure of Optimal Prefix-Free Codes in Restricted Languages: The Uniform Probability Case.- Tradeoffs Between Branch Mispredictions and Comparisons for Sorting Algorithms.- Derandomization of Dimensionality Reduction and SDP Based Algorithms.- Session 9B.- Subquadratic Algorithms for 3SUM.- Near-Optimal Pricing in Near-Linear Time.- Improved Approximation Bounds for Planar Point Pattern Matching.