This book constitutes the refereed proceedings of the 5th Italian Conference on Algorithms and Computation, CIAC 2003, held in Rome, Italy in May 2003.The 23 revised full papers presented were carefully reviewed and selected from 57 submissions. Among the topics addressed are complexity, complexity theory, geometric computing, matching, online algorithms, combinatorial optimization, computational graph theory, approximation algorithms, network algorithms, routing, and scheduling.

Tutorials.- Localized Network Representations.- Optimal Binary Search Trees with Costs Depending on the Access Paths.- On the Generation of Extensions of a Partially Ordered Set.- Error-Correcting Codes in Complexity Theory.- Invited Talks.- Cache-Oblivious Algorithms.- Spanning Trees with Low Maximum/Average Stretch.- Hyper Encryption and Everlasting Secrets.- Computing with Electronic Nanotechnologies.- Regular Contribution.- Efficient Update Strategies for Geometric Computing with Uncertainty.- Maximizing the Guarded Boundary of an Art Gallery Is APX-Complete.- An Improved Algorithm for Point Set Pattern Matching under Rigid Motion.- Unlocking the Advantages of Dynamic Service Selection and Pricing.- The Relative Worst Order Ratio for On-Line Algorithms.- On-Line Stream Merging, Max Span, and Min Coverage.- Randomised Algorithms for Finding Small Weakly-Connected Dominating Sets of Regular Graphs.- Additive Spanners for k-Chordal Graphs.- Graph-Modeled Data Clustering: Fixed-Parameter Algorithms for Clique Generation.- Reconciling Gene Trees to a Species Tree.- Generating All Forest Extensions of a Partially Ordered Set.- Indexing Structures for Approximate String Matching.- Approximation Hardness for Small Occurrence Instances of NP-Hard Problems.- Fast Approximation of Minimum Multicast Congestion - Implementation versus Theory.- Approximation of a Retrieval Problem for Parallel Disks.- On k-Edge-Connectivity Problems with Sharpened Triangle Inequality.- The Complexity of Detecting Fixed-Density Clusters.- Nearly Bounded Error Probabilistic Sets.- Some Properties of MODm Circuits Computing Simple Functions.- XOR-Based Schemes for Fast Parallel IP Lookups.- The Impact of Network Structure on the Stability of Greedy Protocols.- Improving Customer Proximity toRailway Stations.- Differential Approximation for Some Routing Problems.