2679071
A generic operation transformation scheme for consistency maintenance in real-time cooperative editing systems
In real-time cooperative editing systems, independent operations on any part of the shared document may be generatedfrom multiple cooperatingsites. It is very important and technically challenging to ensure that the effect of executing an operation at remote sites, in the presence of concurrent execution of independent operations, achieves the same effect aa executing this operation at the local site at the time -of ita generation, thuspreaeruing its intention and maintainingsystern consistency. In this paper, we investigate the technical issues involved in preserving intentions of concurrent operuCons, explain the reaaons why traditional serialization-based concurrency control strategies and existing operational transformation strategies failed to solve these problems, and propose a generic operation transformation scheme for intention preservation and consistency maintenance in real-time cooperative editing systems. The proposed scheme has been implemented in an Internet-based prototype REDUCE (REaLtime Distributed Unconstrained Cooperative Editing) system. is quick (idealy as quick as a single-user editor) and the latency for remote user actions is low (determined by external commkkation latency only). (2) Distributed environments cooperating users may reside on different machines connected by different communication networks. (3) Unconstrained collaboration mdtiple users may concurrently and freely edit, any part of the document at any time, as advocated in [2, 8, 91.
4914546
Multiple temporal consistency states for dynamical verification of upper bound constraints in grid workflow systems
Conventional upper bound constraint verification in grid workflow systems is based on the key assumption that an upper bound constraint only has two states: consistency and inconsistency. However, due to complexity of grid workflows and dynamic availability of participating grid services, this assumption is too restrictive as there may be some intermediate states. Therefore, in this paper, we introduce four states for an upper bound constraint. Namely, we treat conventional consistency as strong consistency and divide conventional inconsistency into weak consistency, weak inconsistency and strong inconsistency. Correspondingly, we develop their verification methods. For weak consistency, we present some algorithms on how to adjust it to strong consistency without triggering exception handling as in conventional work. For weak inconsistency, we analyse why it can rely on less costly exception handling than conventional work. The final evaluation demonstrates that our four-state approach can achieve better cost-effectiveness than the conventional two-state approach
14000419
Using an experimental study to develop group awareness support for real-time distributed collaborative writing
Supporting group awareness is vital for the success of real-time, distributed, collaborative writing systems. Many awareness mechanisms have been introduced, but highly effective solutions are few. The research presented in this paper focuses on the development of awareness mechanisms using an experimental study of synchronous distributed collaborative writing. Our study has made two major contributions to research on group awareness. First, the study compares the importance of different awareness elements in supporting group awareness for collaborative writing. The results of our Wilcoxon test on awareness elements identify the five most important elements, including ‘‘Being able to comment on what other users have done,’’ ‘‘Knowing what actions other users are currently taking,’’ ‘‘Providing a communication tool when audio is not available,’’ ‘‘Knowing other user’s working areas in the document,’’ and ‘‘Knowing other user’s tasks.’’ Second, the research proposes mechanisms corresponding to the above-mentioned five awareness elements. The mechanisms include Dynamic Task List (DTL), Modification Director (MD), Advanced Chat (AC) and Split Window View (SWV). These mechanisms provide support for various aspects of group awareness, and add many enhanced features to existing awareness mechanisms. For example, DTL presents high-level information about authors’ responsibilities and the correlation between their work allocations. MD notifies users instantaneously whenever their work is modified by other authors. AC enhances communication between users by allowing them to attach document objects such as text and diagrams to a conversation message. And, SWV provides the views of other authors’ working areas and viewing areas simultaneously. � 2005 Elsevier B.V. All rights reserved.
4924842
Assigning Local Fixed-time Constraints in Grid Workflow Systems
Many complex grid workflow processes often have only one global fixed-time constraint at the last activity. Since grid workflow execution normally lasts a long time, local control is very important to ensure the overall temporal correctness. With only one global fixed-time constraint, we cannot control grid workflow execution locally in terms of time. As a result, for any temporal violations, we must handle them globally with the consideration of all activities. This would impact the overall cost-effectiveness of grid workflow execution. Therefore, in this paper, we investigate how to assign local fixed-time constraints within the global one so that we can control grid workflow execution locally. Corresponding assigning and verification methods are developed. With local fixed-time constraints, we can achieve better cost-effectiveness
16079123
Agent-Based Ontology Mapping Towards Ontology Interoperability
Globalisation of business environments on the Web has given rise to the advent of similar ontologies in which dynamic ontology mapping is called in. Ontology mapping is necessary for ontology interoperability. In this paper, a novel agent-based ontology mapping is presented for agents to operate ontology mapping flexibly in a dynamic environment regardless heterogeneous platforms and different ontology representations. The mapping mechanism is discussed by having a close look at both inherent inter-processes of mapping tasks of an agent and relevant interaction processes. The interrelated processes of agents also enable agent-based ontology mapping to take ontology changes into account whenever needed. A mapping prototype is built for verification.
14447070
Achieving convergence, causality preservation, and intention preservation in real-time cooperative editing systems
Real-time cooperative editing systems allow multiple users to view and edit the same text/graphic/image/multimedia document at the same time for multiple sites connected by communication networks. Consistency maintenance is one of the most significant challenges in designing and implementing real-time cooperative editing systems. In this article, a consistency model, with properties of convergence, causality preservation, and intention preservation, is proposed as a framework for consistency maintenance in real-time cooperative editing systems. Moreover, an integrated set of schemes and algorithms, which support the proposed consistency model, are devised and discussed in detail. In particular, we have contributed (1) a novel generic operation transformation control algorithm for achieving intention preservation in combination with schemes for achieving convergence and causality preservation and (2) a pair of reversible inclusion and exclusion transformation algorithms for stringwise operations for text editing. An Internet-based prototype system has been built to test the feasibility of the proposed schemes and algorithms
6002635
Improving text categorization methods for event tracking
Automated tracking of events from chronologically ordered document streams is a new challenge for statistical text classification. Existing learning techniques must be adapted or improved in order to effectively handle difficult situations where the number of positive training instances per event is extremely small, the majority of training documents are unlabelled, and most of the events have a short duration in time. We adapted several supervised text categorization methods, specifically several new variants of the k-Nearest Neighbor (kNN) algorithm and a Rocchio approach, to track events. All of these methods showed significant improvement (up to 71% reduction in weighted error rates) over the performance of the original kNN algorithm on TDT benchmark collections, making kNN among the top-performing systems in the recent TDT3 official evaluation. Furthermore, by combining these methods, we significantly reduced the variance in performance of our event tracking system over different data collections, suggesting a robust solution for parameter optimization.
8861403
Design and implementation of the just-in-time retrieving policy for schedule-based distributed multimedia presentations
In order to provide the smooth playback of a distributed multimedia presentation, the object-retrieving engine for the player must fetch each object before its playback time. In this paper, a smart object-retrieving engine is proposed, which adopts a retrieving policy named the just-in-time policy. The policy expects the retrieval process of an object to finish right before the playback time of the object to achieve a better buffer utilization and network bandwidth efficiency. The proposed object-retrieving engine focuses on SMIL1.0-based multimedia presentations. By converting the synchronization relationship of objects in the SMIL 1.0 document to Real-Time Synchronization Model, which simplifies the handling of the synchronization relationship, and considering the end-to-end bandwidth as well as the user interactions, the object-retrieving engine determines the object request time for each object. The engine issues the request to fetch each object for the ongoing presentation at the object request time, and provides the player with proper media objects. The feasibility and better performance of the proposed just-in-time retrieving policy had been proved by performance measurements of system implementation.
10222228
The third Ramsey numbers for graphs with at most four edges
Abstract With the help of a computer, the Ramsey numbers r 3 ( H ) are obtained for each of the 19 graphs H with at most four edges and no isolated vertices.
14181364
Probabilistic score estimation with piecewise logistic regression
Well-calibrated probabilities are necessary in many applications like probabilistic frameworks or cost-sensitive tasks. Based on previous success of asymmetric Laplace method in calibrating text classifiers' scores, we propose to use piecewise logistic regression, which is a simple extension of standard logistic regression, as an alternative method in the discriminative family. We show that both methods have the flexibility to be piecewise linear functions in log-odds, but they are based on quite different assumptions. We evaluated asymmetric Laplace method, piecewise logistic regression and standard logistic regression over standard text categorization collections (Reuters-21578 and TRECAP) with three classifiers (SVM, Naive Bayes and Logistic Regression Classifier), and observed that piecewise logistic regression performs significantly better than the other two methods in the log-loss metric.
2067202
On self adaptive routing in dynamic environments - an evaluation and design using a simple, probabilistic scheme
Recently we have seen an emergent trend of self adaptive routing in both Internet and wireless ad hoc networks. Although there are previous methods for computing the traffic equilibria of self adaptive routing (e.g., selfish routing), these methods use computationally demanding algorithms and require that a precise analytical model of the network be given. Also, it remains an open question how to design an adaptive routing scheme which ensures convergence to traffic equilibria in practice. In this paper we propose a simple, efficient, distributed probabilistic routing scheme for self adaptive routing in dynamic, realistic environments. Using both analysis and extensive simulations, we show that our scheme can converge to the desired traffic equilibrium (either user-optimal or network-optimal) very quickly. We find that user-optimal routing can achieve very close to optimal average latency in dynamic environments, but such performance often comes at the cost of seriously overloading certain links. To avoid link overloads, we improve adaptive routing by optimizing average user latency and link utilization simultaneously. Our evaluation shows that there is a trade-off between optimizing dual objectives, but the degradation in average latency is only marginal for typical link utilization requirements.