Mechanical verification of the IEEE 1394a root contention protocol using Uppaal2k

This paper reports on the mechanical verification of the IEEE 1394 root contention protocol. This is an industrial leader election protocol, in which timing parameters play an essential role. A manual verification of this protocol using I/O automata has been published in [24]. We improve the communication model presented in that paper. Using the Uppaal2k tool, we investigate the timing constraints on the parameters which are necessary and sufficient for correct protocol operation: by analyzing large numbers of protocol instances with different parameter values, we derive the required timing constraints. We explore the use of model checking in combination with stepwise abstraction. That is, we show that the implementation automaton correctly implements the specification via several intermediate automata, using Uppaal to prove the trace inclusion in each step. Published online: 18 July 2001     

Large scale address recognition systems Truthing,testing, tools,and other evaluation issues

This paper describes the issues involved in the design of a system for evaluating improvements in the performance of a real-time address recognition system being used by the United States Postal Service for processing mail-piece images. Evaluation of the performance of recognition systems is normally carried out by measuring the performance of the system on a representative sample of images. Designing a comprehensive and valid testing scenario is a complex task that requires careful attention. Sampling live mail-stream to generate a deck of images representative of the general mail-stream for testing, truthing (generating reference data on a significant number of images), grading and evaluation, and designing tools to facilitate these functions are important topics that need to be addressed. This paper describes the efforts of the United States Postal Service and CEDAR towards developing an infrastructure for sampling, truthing, and testing of mail-stream images. Received: July 25, 2000 / Revised version: July 31, 2001     

The optimal location of replicas in a network using a READ-ONE-WRITE-ALL policy

We consider the problem of locating replicas in a network to minimize communications costs. Under the assumption that the read-one-write-all policy is used to ensure data consistency, an optimization problem is formulated in which the cost function estimates the total communications costs. The paper concentrates on the study of the optimal communications cost as a function of the ratio between the frequency of the read and write operations. The problem is reformulated as a zero-one linear programming problem, and its connection to the p-median problem is explained. The general problem is proved to be NP-complete. For path graphs a dynamic programming algorithm for the problem is presented. Received: May 1993 / Accepted: June 2001     

Modeling a Murex cabritii sea shell with a structured implicit surface modeler

BlobTree , and its application to the generation of a complex and visually accurate biological model of the sea shell Murex cabritii. Since the model is purely procedurally defined and does not rely on polygon mesh operations, it is resolution independent and can be rendered directly using ray tracing. An interface has been built for the BlobTree using an interpreted programming language (Python). The language interface readily allows a user to procedurally describe the shell based on numeric data taken from the actual object. Published online: 15 March 2002     

Automatic Verification of a Lip-Synchronisation Protocol Using Uppaal

We present the formal specification and verification of a lip-synchronisation protocol using the real-time model checker Uppaal. A number of specifications of this protocol can be found in the literature, but this is the first automatic verification. We take a published specification of the protocol, code it up in the Uppaal timed automata notation and then verify whether the protocol satisfies the key properties of jitter and skew. The verification reveals some aws in the protocol. In particular, it shows that for certain sound and video streams the protocol can time-lock before reaching a prescribed error state. We also discuss our experience with Uppaal, with particular reference to modelling timeouts and to deadlock analysis. Received March 1998 / Accepted in revised form October 1998     

Interactive authoring of multimedia documents in a constraint-based authoring system

As multimedia applications spread widely, it is crucial for programming and design support systems to handle “time” in multimedia documents effectively and flexibly. This paper presents a set of interactive system support tools for designing and maintaining the temporal behavior of multimedia documents. The tool set provides mechanisms for anomaly detection, temporal query processing, and interactive scheduling. It is based on a fast incremental constraint solver we have developed, which can be adapted by any constraint-based system. The incremental constraint solver provides immediate feedback to the user, supporting a highly interactive design process. Combined with existing optimal layout generation mechanisms proposed in the literature, our tools effectively utilize the flexibility provided by constraint-based systems.     

Analysis,management and indexing of distributed multimedia performances based on audience feedback

Interactive performance systems allow multiple, networked users to take part in a performance either as players or audience members and influence the performance's development in real time. Among the most prominent research issues concerning the development of these systems are the provision of effective interaction capabilities and adequate means of expression to the audience. This article describes a set of methods for the detection, analysis, synchronization and rendering of audience behavior in real-time during such an event. Furthermore, it describes ways in which audience feedback is utilized to dynamically index the contents of a performance so as to embed this event in large-scale multimedia services. All these methods have been applied in the creation of MISSION, a multi-user game involving both players and audience. This article presents and analyzes the design of the system and the results of user trials with it.