Theoretical Aspects of Computing - ICTAC 2009

ThisvolumecontainsthepaperspresentedatICTAC2009:the6thInternational Colloquium on Theoretical Aspects of Computing held August 18-20, 2009 in Kuala Lumpur, Malaysia, hosted by Universiti Kebangsaan Malaysia. The ICTAC series was founded by the International Institute for Software Technology of the United Nations University (UNU-IIST). It brings together practitionersandresearchersfromacademia,industryandgovernmenttopresent results and to exchange ideas and experience addressing challenges in both t- oretical aspects of computing and in the exploitation of theory through me- ods and tools for system development. The series also promotes cooperation in research and education between participants and their institutions, from dev- oping and industrial countries, in accordance with the mandate of the United Nations University. The previous ICTAC colloquia were held in Guiyang, China (2004, LNCS 3407), Hanoi, Vietnam (2005, LNCS 3722), Tunis, Tunisia (2006, LNCS 4281), Macao SAR, China (2007, LNCS 4711), and Istanbul, Turkey (2008, LNCS 5160). This year, 81 submissions were received, distributed over 70 full research papers and 11 tool papers. Each submission was reviewed by at least three P- gram Committee members. We thank the members of the Program Committee and the other specialist referees for the e?ort and skill that they invested in the review and selection process, which was managed using EasyChair. The C- mittee decided to accept 20 papers: 17 full research papers and 3 tool papers.

Invited Papers.- Static Analysis of Concurrent Programs Using Ordinary Differential Equations.- The PlusCal Algorithm Language.- The Secret Art of Computer Programming.- Verification, Testing and Statistics.- Full Research Papers.- ?-Types for Effects and Freshness Analysis.- A First-Order Policy Language for History-Based Transaction Monitoring.- Checking Thorough Refinement on Modal Transition Systems Is EXPTIME-Complete.- Transmission Protocols for Instruction Streams.- A Deadlock-Free Semantics for Shared Memory Concurrency.- On the Expressiveness of Forwarding in Higher-Order Communication.- On the Hairpin Completion of Regular Languages.- Context-Free Languages of Countable Words.- Automatic Conflict Detection on Contracts.- A Sound Observational Semantics for Modal Transition Systems.- Regular Expressions with Numerical Constraints and Automata with Counters.- On the Relative Expressive Power of Contextual Grammars with Maximal and Depth-First Derivations.- Integration Testing from Structured First-Order Specifications via Deduction Modulo.- A Minimized Assumption Generation Method for Component-Based Software Verification.- A Formal Approach to Heuristically Test Restorable Systems.- Constrained Reachability of Process Rewrite Systems.- Input-Output Model Programs.- Tool Papers.- IMITATOR: A Tool for Synthesizing Constraints on Timing Bounds of Timed Automata.- GSPeeDI - A Verification Tool for Generalized Polygonal Hybrid Systems.- Hierarchical Graph Rewriting as a Unifying Tool for Analyzing and Understanding Nondeterministic Systems.