Contributed Talks -- Online Coloring of Intervals with Bandwidth -- Open Block Scheduling in Optical Communication Networks -- Randomized Priority Algorithms -- Tradeoffs in Worst-Case Equilibria -- Load Balancing of Temporary Tasks in the ? p Norm -- Simple On-Line Algorithms for Call Control in Cellular Networks -- Fractional and Integral Coloring of Locally-Symmetric Sets of Paths on Binary Trees -- A -Approximation Algorithm for Scheduling Identical Malleable Tasks -- Optimal On-Line Algorithms to Minimize Makespan on Two Machines with Resource Augmentation -- Scheduling AND/OR-Networks on Identical Parallel Machines -- Combinatorial Interpretations of Dual Fitting and Primal Fitting -- On the Approximability of the Minimum Fundamental Cycle Basis Problem -- The Pledge Algorithm Reconsidered under Errors in Sensors and Motion -- The Online Matching Problem on a Line -- How to Whack Moles -- Online Deadline Scheduling: Team Adversary and Restart -- Minimum Sum Multicoloring on the Edges of Trees -- Scheduling to Minimize Average Completion Time Revisited: Deterministic On-Line Algorithms -- On-Line Extensible Bin Packing with Unequal Bin Sizes -- ARACNE Talks -- Energy Consumption in Radio Networks: Selfish Agents and Rewarding Mechanisms -- Power Consumption Problems in Ad-Hoc Wireless Networks -- A Combinatorial Approximation Algorithm for the Multicommodity Flow Problem -- Disk Graphs: A Short Survey -- Combinatorial Techniques for Memory Power State Scheduling in Energy-Constrained Systems.

The Workshop on Approximation and Online Algorithms (WAOA 2003) focused on the design and analysis of algorithms for online and computationally hard problems. Both kinds of problems have a large number of applications ar- ing from a variety of ?elds. The workshop also covered experimental research on approximation and online algorithms. WAOA 2003 took place in Budapest, Hungary, from September 16 to September 18. The workshop was part of the ALGO 2003 event, which also hosted ESA 2003, WABI 2003, and ATMOS 2003. TopicsofinterestforWAOA2003were:competitiveanalysis,inapproximab- ityresults,randomizationtechniques,approximationclasses,scheduling,coloring and partitioning, cuts and connectivity, packing and covering, geometric pr- lems, network design, and applications to game theory and ?nancial problems. In response to our call for papers we received 41 submissions. Each submission was reviewed by at least 3 referees, who judged the papers on originality, quality, and consistency with the topics of the conference. Based on these reviews the program committee selected 19 papers for presentation at the workshop and for publication in this proceedings. This volume contains the 19 selected papers and 5 invited abstracts from an ARACNE minisymposium which took place as part of WAOA.