7877505
Three forbidden subgraphs for line graphs
We construct a set of three graphs with the property that a 3-connected graph with minimum degree at least 7 is a line graph if and only if it does not contain any of the three graphs as an induced subgraph. We also show that the number of excluded subgraphs cannot be reduced no matter what connectivity is specified.
205877442
On distinct distance sets in a graph
A distinct distance set (DD set) for a graph G is a vertex subset of G with the property that for vbSvb = s, we have (2s) distinct distances of the pairs of vertices in S.In this article, it is shown that(a) For 6 ? k ? 18 there exists a tree T with DD(T) = k and dm(T) = LB(k) < B1(Kk), where LB(k) is the smallest value L for which there are positive integers A and B with A+B=k, A2+B2??L2?, AB??L2?.(b) For k ? 10, the minimum order of a tree T with DD(T) = k is B1(Kk), which is the order of the corresponding Colomb ruler for k.
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.
12472387
CLID: A general approach to validate security policies in a dynamic network
Many researchers have considered security policy management, including how to configure policies manually and even how to automatically generate security policies based on security requirements. Both can be error prone, especially when properties of the network topology change, because security requirements are usually not bound to any particular route path. Our DETER lab emulation results show that conflicts could be caused by these factors. Therefore, a systematic way to validate the correctness of the security policies is essential. This paper presents an approach, CLID (conflict and looping identification and detection), to verify whether a set of security policies (e.g. IPSec/VPN tunnels) satisfy the given security requirements, without causing any conflicts. This approach utilizes the definition of a security policy lo include network routing data as well as traffic selector information, thus it works for general network topologies. We also analyze and justify the correctness of the approach. The paper concludes with our simulation results and addresses future work.
17059698
Towards composing information providing services
Composing Web services is an active field of research and development. Recently, many efforts are devoted to process integration on world changing services, e.g. business process composition. We present a solution to compose information providing services to achieve more powerful capabilities and free the user from trivial work. Our work serves as an important complement to the existing research on process integration.
2911118
A Theory of Network Localization
In this paper, we provide a theoretical foundation for the problem of network localization in which some nodes know their locations and other nodes determine their locations by measuring the distances to their neighbors. We construct grounded graphs to model network localization and apply graph rigidity theory to test the conditions for unique localizability and to construct uniquely localizable networks. We further study the computational complexity of network localization and investigate a subclass of grounded graphs where localization can be computed efficiently. We conclude with a discussion of localization in sensor networks where the sensors are placed randomly
34587947
Guaranteed Mutually Consistent Checkpointing in Distributed Computations
In this paper, we emplore the isomorphism between vector time and causality to characterize consistency of a set of checkpoints in a distributed computing. A necessary and sufficient condition, to determine if a set of checkpoints can form a consistent global checkpoint, is presented and proved using the isomorphic power of vector time and causality. To the best of our knowledge, this is the first attempt to use the isomorphism for this purpose. This condition leads to a simple and straightforward algorithm for a guaranteed mutually consistent global checkpointing. In our approach, a process can take a checkpoint whenever and wherever it wants while other related process may be asked to take an additional checkpoint for ensuring the mutual consistency. We also show how this condition and the resulting algorithm can be used to obtain a maximum and minimum global checkpoints, another important paradigm for distributed applications.
599278
Extending RDF in distributed knowledge-intensive applications
The resource description framework (RDF) has become a formal language tool to specify the semantics of distributed systems, such as web services nowadays. In fact, it can also be extended to describe entities and relationships within specific application environments to support knowledge sharing and ontology construction. This paper presents two case studies on a network management knowledge model and a distributed workflow system process ontology. With practical experiences, the authors suggest how RDF can be applied innovatively and effectively to reengineer data integration solutions in different novel knowledge-intensive areas, which, in the past, were built upon traditional modelling languages, such as XML.