7961359
LexTrim: A Lexical Cohesion Based Approach to Parse-and-Trim Style Headline Generation
In this paper we compare two parse-and-trim style headline generation systems. The Topiary system uses a statistical learning approach to finding topic labels for headlines, while our approach, the LexTrim system, identifies key summary words by analysing the lexical cohesion structure of a text. The performance of these systems is evaluated using the ROUGE evaluation suite on the DUC 2004 news stories collection.
36952841
Textual CBR for Incident Report Retrieval
Incident Management Systems can play a crucial role in helping to reduce the number of workplace accidents by providing support for incident analysis. In particular, the retrieval of relevant similar incident reports can help safety personnel to identify factors and patterns that have contributed or might potentially contribute to accidents. Incident Report Retrieval is a relatively new research topic in the field of Accident Reporting and Analysis, and we are interested in developing intelligent computational support for retrieving incident information that leverages both the featural and textual components of incident reports. This paper describes InRet-T, an Incident Report Retrieval system that incorporates approaches from textual case-based reasoning to integrate both featural and textual aspects in retrieving civil aviation incident reports. It also provides a preliminary evaluation of InRet-T that offers some insight into the use of textual CBR approaches to incident analysis.
35854986
News Headline Generation based on Linguistic Methods
5449095
Experience with a Language for Writing Coherence Protocols
In this paper we describe our experience with Teapot [7], a domain-specific language for writing cache coherence protocols. Cache coherence is of concern when parallel and distributed computing systems make local replicas of shared data to improve scalability and performance. In both distributed shared memory systems and distributed file systems, a coherence protocol maintains agreement among the replicated copies as the underlying data are modified by programs running on the system. 
 
Cache coherence protocols are notoriously difficult to implement, debug, and maintain. Unfortunately, protocols are not off-the-shelf items, as their details depend on the requirements of the system under consideration. This paper presents case studies detailing the successes and shortcomings of using Teapot for writing coherence protocols in two systems. The first system, loosely coherent memory (LCM) [16], implements a particular type of distributed shared memory suitable for data-parallel programming. The second system, the xFS distributed file system [9], implements a high-performance, serverless file system. 
 
Our overall experience with Teapot has been very positive. In particular, Teapot's language features resulted in considerable simplifications in the protocol source code for both systems. Furthermore, Teapot's close coupling between implementation and formal verification helped to achieve much higher confidence in our protocol implementations than previously possible and reduced the time to build the protocols. By using Teapot to solve real problems in complex systems, we also discovered several shortcomings of the Teapot design. Most noticeably, we found Teapot lacking in support for multithreaded environments, for expressing actions that transcend several cache blocks, and for handling blocking system calls. We believe that domain-specific languages are valuable tools for writing cache coherence protocols.
6622555
A quantitative analysis of cache policies for scalable network file systems
Current network file system protocols rely heavily on a central server to coordinate file activity among client workstations. This central server can become a bottleneck that limits scalability for environments with large numbers of clients. In central server systems such as NFS and AFS, all client writes, cache misses, and coherence messages are handled by the server. To keep up with this workload, expensive server machines are needed, configured with high-performance CPUs, memory systems, and I/O channels. Since the server stores all data, it must be physically capable of connecting to many disks. This reliance on a central server also makes current systems inappropriate for wide area network use where the network bandwidth to the server may be limited.
In this paper, we investigate the quantitative performance effect of moving as many of the server responsibilities as possible to client workstations to reduce the need for high-performance server machines. We have devised a cache protocol in which all data reside on clients and all data transfers proceed directly from client to client. The server is used only to coordinate these data transfers. This protocol is being incorporated as part of our experimental file system, xFS. We present results from a trace-driven simulation study of the protocol using traces from a 237 client NFS installation. We find that the xFS protocol reduces server load by more than a factor of six compared to AFS without significantly affecting response time or file availability.
13692739
Modeling communication pipeline latency
In this paper, we study how to minimize the latency of a message through a network that consists of a number of store-and-forward stages. This research is especially relevant for today's low overhead communication systems that employ dedicated processing elements for protocol processing. We develop an abstract pipeline model that reveals a crucial performance tradeoff involving the effects of the overhead of the bottleneck stage and the bandwidth of the remaining stages. We exploit this tradeoff to develop a suite of fragmentation algorithms designed to minimize message latency. We also provide an experimental methodology that enables the construction of customized pipeline algorithms that can adapt to the specific system characteristics and application workloads. By applying this methodology to the Myrinet-GAM system, we have improved its latency by up to 51%. Our theoretical framework is also applicable to pipelined systems beyond the context of high speed networks.
208003557
Serverless network file systems
We propose a new paradigm for network file system design: serverless network file systems. While traditional network file systems rely on a central server machine, a serverless system utilizes workstations cooperating as peers to provide all file system services. Any machine in the system can store, cache, or control any block of data. Our approach uses this location independence, in combination with fast local area networks, to provide better performance and scalability than traditional file systems. Furthermore, because any machine in the system can assume the responsibilities of a failed component, our serverless design also provides high availability via redundatn data storage. To demonstrate our approach, we have implemented a prototype serverless network file system called xFS. Preliminary performance measurements suggest that our architecture achieves its goal of scalability. For instance, in a 32-node xFS system with 32 active clients, each client receives nearly as much read or write throughput as it would see if it were the only active client.
8792310
xFS: a wide area mass storage file system
The current generation of file systems are inadequate in facing the new technological challenges of wide area networks and massive storage. xFS is a prototype file system we are developing to explore the issues brought about by these technological advances. xFS adapts many of the techniques used in the field of high performance multiprocessor design. It organizes hosts into a hierarchical structure so locality within clusters of workstations can be better exploited. By using an invalidation-based write back cache coherence protocol, xFS minimizes network usage. It exploits the file system naming structure to reduce cache coherence state. xFS also integrates different storage technologies in a uniform manner. Due to its intelligent use of local hosts and local storage, we expect xFS to achieve better performance and availability than current generation network file systems run in the wide area.<<ETX>>