Distributed MAP in the SpinJa Model Checker

Spin in Java (SpinJa) is an explicit state model checker for the Promela modelling language also used by the SPIN model checker. Designed to be extensible and reusable, the implementation of SpinJa follows a layered approach in which each new layer extends the functionality of the previous one. While SpinJa has preliminary support for shared-memory model checking, it did not yet support distributed-memory model checking. This tool paper presents a distributed implementation of a maximal accepting predecessors (MAP) search algorithm on top of SpinJa.Comment: In Proceedings PDMC 2011, arXiv:1111.006

Verifying Real-Time Systems using Explicit-time Description Methods

Timed model checking has been extensively researched in recent years. Many new formalisms with time extensions and tools based on them have been presented. On the other hand, Explicit-Time Description Methods aim to verify real-time systems with general untimed model checkers. Lamport presented an explicit-time description method using a clock-ticking process (Tick) to simulate the passage of time together with a group of global variables for time requirements. This paper proposes a new explicit-time description method with no reliance on global variables. Instead, it uses rendezvous synchronization steps between the Tick process and each system process to simulate time. This new method achieves better modularity and facilitates usage of more complex timing constraints. The two explicit-time description methods are implemented in DIVINE, a well-known distributed-memory model checker. Preliminary experiment results show that our new method, with better modularity, is comparable to Lamport's method with respect to time and memory efficiency

Platform Dependent Verification: On Engineering Verification Tools for 21st Century

The paper overviews recent developments in platform-dependent explicit-state LTL model checking.Comment: In Proceedings PDMC 2011, arXiv:1111.006

The distributed ASCI supercomputer project

The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project

Using Group Communication to Implement a Fault-Tolerant Directory Service

Group communication is an important paradigm for building distributed applications. This paper discusses a fault-tolerant distributed directory service based on group communication, and compares it with the previous design and implementation based on remote procedure call. The group directory service uses an active replication scheme and, when triplicated, can handle 627 lookup operations per second and 88 update operations per second (using nonvolatile RAM). This performance is better than the performance for the RPC implementation and it is even better than the performance for directory operations under SunOS, which does not provide any fault tolerance at all. The paper concludes that the implementation using group communication is simpler and has better performance than the one based on remote procedure call, supporting the claim that a distributed operating system should provide both remote procedure call and group communication

Communicatie van statistische informatie over onzekerheid bij de beheersing van risico’s van wateroverlast

Onzekerheidsanalyse is niet vanzelfsprekend bij de onderbouwing van beslissingen in het strategisch kwantitatief waterbeheer. Toch is informatie over onzekerheid nuttig, omdat inzicht in risico’s en daaraan gerelateerde kosten en baten bijdraagt aan de doelmatigheid van beslissingen. We onderzochten daarom de rol van statistische informatie over onzekerheid bij strategische beslissingen van waterschappen bij het beheersen van risico’s van wateroverlast: hoe wordt deze informatie gepresenteerd, geïnterpreteerd en benut, en ook of de communicatie over statistisch gekwantificeerde onzekerheid kan worden verbeterd