7717414
A time interval based consistency control algorithm for interactive groupware applications
Traditional concurrency control methods such as locking and serialization are not suitable for distributed interactive applications that demand fast local response. Operational transformation (OT) is the standard solution to concurrency control and consistency maintenance in group editors, an important class of interactive groupware applications. It generally trades consistency for local responsiveness, because human users can often tolerate temporary inconsistencies but do not like their interactions be lost or nondeterministically blocked. This paper presents a time interval based operational transformation algorithm (TIBOT) that overcomes the various limitations of previous related work. Our approach guarantees content convergence and is significantly more simple and efficient than existing approaches. This is achieved in a pure replicated architecture by using a linear clock and by posing some constraints on communication that are reasonable for the application domain.
17885452
Commutativity-based concurrency control in groupware
Commutativity of operations is often exploited in concurrent systems to attain high levels of concurrency. A commutativity-based concurrency control method, called operational transformation (OT), has been actively researched in groupware over the past 15 years. However, much progress can still be made on more practicable approaches to developing and proving OT algorithms. Several constraints have been proposed previously but they are generally difficult to follow and verify in practice. This paper proposes an alternative approach to address this problem. A new consistency model is defined which greatly simplifies the design and proof of OT algorithms
6775901
Hamiltonicity of 3-connected quasi-claw-free graphs
A graph G is called quasi-claw-free if it satisfies the property: d(x,y)[email protected]? there exists [email protected]?N(x)@?N(y) such that N[u]@?N[x]@?N[y]. Let G be a 3-connected quasi-claw-free graph of order n. If @d(G)>=(n+5)/5, then G is hamiltonian.
13976225
WebPeer: A P2P-based system for publishing and discovering Web services
The use of Web services as an infrastructure of service sharing has made it possible to provide collaboration and interoperability in distributed computing environment. In this environment, service publishing and discovery are required as elementary functionalities for users to be able to locate the shared resources. The mechanism of service publishing and discovery with centralized architecture restricts the reliability and scalability of the distributed computing environment as the services and resources on the Web are fast emerging. The peer-to-peer (P2P) systems and applications, on the other hand, employ distributed resources to perform critical functions in a decentralized manner. This paper introduces Web Services Oriented Peer-to-peer (WSOP) architecture with a combination of centralized and decentralized characteristics, and presents a framework of service publishing and discovery model based on WSOP architecture. The prototype system - WebPeer implemented based on this model demonstrates the WSOP architecture can not only help to overcome the known obstacles in common Web Services infrastructure such as single node failure, but also extend the ability of the pure P2P systems, such as more efficiently locating the resources, increasing the interoperability between different P2P systems.
2594812
Evaluation of the Geopositioning Accuracy of QuickBird Imagery
QuickBird satellite imagery, provided by DigitalGlobe Inc., has the highest resolution, among the satellite imaging systems that are commercially available. The QuickBird imaging system simultaneously collects 67-72 centimeter resolution stereo panchromatic and 2.44-2.88 meter resolution multispectral images. In this research, a QuickBird stereo pair of basic imagery product that was taken over Tampa Bay, FL, was acquired and its geopositioning accuracy evaluated based on Rational Function (RF) models.
2080269
Testing multivariate uniformity and its applications
Some new statistics are proposed to test the uniformity of random samples in the multidimensional unit cube [0, 1] d (d ≥ 2). These statistics are derived from number-theoretic or quasi-Monte Carlo methods for measuring the discrepancy of points in [0,1] d Under the null hypothesis that the samples are independent and identically distributed with a uniform distribution in [0,1] d , we captain some asymptotic properties of the new statistics. By Monte Carlo simulation, it is found that the finite-sample distributions of the new statistics are well approximated by the standard normal distribution, N(0,1), or the chi-squared distribution, X 2 (2). A power study is performed, and possible applications of the new statistics to testing general multivariate goodness-of-fit problems are discussed.
41530847
A Note on Hamiltonian Cycles in K(1, r)-Free Graphs