. This paper studies the usage of broadcast communication in distributed services. The approach taken is practical: all the algorithms are asynchronous, and tolerate realistic faults. We study four problems in a broadcast domain: clock synchronization, reliable and ordered broadcast, membership

This paper presents the construction of a multicast service, called agreed multicast, that guarantees that messages arrive reliably and in the same total-order to all their destinations. ToTo, a novel family of protocols, implement the agreed multicast service of Transis, a communication sub-system for the High Availability project, currently developed at the Hebrew University of Jerusalem. This service is desired in distributed systems, and supports high level coordination among groups of processes in distributed applications. The ToTo protocols are genuinely symmetric. They are fairly simple and do not bear a significant processing burden. The cost of symmetric total ordering protocols can be measured by the number of messages from different machines needed to agree on the next set of messages to be delivered in total order. The ToTo protocols provide early delivery latency, and require as little as n 2 messages for delivery. Thus, we optimize the time that elapses from the point ...

wieselthier @ itd.nrl.navy.mil nguyen @ itd.nrl.navy.mil

The availability of small inexpensive sensor elements enables the employment of large wired or wireless sensor networks for feeding control systems. Unfortunately, the need to transmit a large number of sensor measurements over a network negatively affects the timing parameters of the control loop. This paper presents a solution to this problem by representing sensor measurements with an approximate representation--- an interpolation of sensor measurements as a function of space coordinates. A priority-based medium access control (MAC) protocol is used to select the sensor messages with high information content. Thus, the information from a large number of sensor measurements is conveyed within a few messages. This approach greatly reduces the time for obtaining a snapshot of the environment state and therefore supports the real-time requirements of feedback control loops.

not be suitable for underwater use. We consider how to time schedule each link in a broadcast domain once. We show that, unlike its terrestrial RF counterpart, this problem is NP complete. We then use a complete SAT solver to investigate the relation between the schedule length and the satisfiability of a given

Many AI researchers are today striving to build agent teams for complex, dynamic multi-agent domains, with intended applications in arenas such as education, training, entertainment, information integration, and collective robotics. Unfortunately, uncertainties in these complex, dynamic domains

Computing semantic relatedness of natural language texts requires access to vast amounts of common-sense and domain-specific world knowledge. We propose Explicit Semantic Analysis (ESA), a novel method that represents the meaning of texts in a high-dimensional space of concepts derived from

model is able to deal with domain-specific synonymy as well as with polysemous words. In contrast to standard Latent Semantic Indexing (LSI) by Singular Value Decomposition, the probabilistic variant has a solid statistical foundation and defines a proper generative data model. Retrieval experiments

(AWGN) channels, which may be good models for hybrid transmission applications such as digital audio broadcasting, and mean-square-error-constrained attack channels that model private-key watermarking applications.

deteriorate under such conditions. This paper reports on the design, construction, and experimental analysis of DiSCo, a German corpus for the evaluation of speech and speaker recognition on challenging material from the broadcast domain. One of the key requirements for the design of this corpus was a good