7153278
Maximum genus and girth of graphs
Abstract In this paper, a lower bound on the maximum genus of a graph in terms of its girth is established as follows: let G be a simple graph with minimum degree at least three, and let g be the girth of G. Then γ(G)⩾ g−2 2(g−1) β(G)+ 1 g−1 except for G=K 4 , where β(G) denotes the cycle rank of G and K4 is the complete graph with four vertices.
8485722
The maximum genus of graphs with diameter three
Abstract This paper shows that if G is a simple graph with diameter three then G is up-embeddable unless G is either a Δ2-graph (Fig. 1) or a Δ3-graph (Fig. 2) with ξ(G) = 2, i.e., the maximum genus γM(G) = (β(G) − 2)/2.
39392055
Maximum genus and chromatic number of graphs
Let T be a spanning tree of a connected graph G. Denote by @x(G,T) the number of components in [email protected]?E(T) with odd number of edges. The value min"[email protected](G,T) is known as the Betti deficiency of G, denoted by @x(G), where the minimum is taken over all spanning trees T of G. It is known (N.H. Xuong, J. Combin. Theory 26 (1979) 217-225) that the maximum genus of a graph is mainly determined by its Betti deficiency @x(G). Let G be a k-edge-connected graph (k=<3) whose complementary graph has the chromatic number m. In this paper we prove that the Betti deficiency @x(G) is bounded by a function f"k(m) on m, and the bound is the best possible. Thus by Xuong's maximum genus theorem we obtain some new results on the lower bounds of the maximum genus of graphs.
12850870
Supporting Mobile Multimedia Services with Intermittently Available Grid Resources
Advances in high quality digital wireless networks and differentiated services have enabled the development of mobile multimedia applications that can execute in global infrastructures. In this paper, we introduce a novel approach to supporting mobile multimedia services by effectively exploiting the intermittently available idle computing, storage and communication resources in a Grid infrastructure. Specifically, we develop efficient resource discovery policies that can ensure continuous access to information sources and maintain application Quality-of-Service (QoS) requirements, e.g. required network transmission bandwidth on the mobile clients. Our performance studies indicate that mobility patterns obtained via tracking or user-supplied itineraries assist in optimizing resource allocation. The proposed policies are also resilient to dynamic changes in the availability of grid resources.
2832131
Applying Data Mining to Pseudo-Relevance Feedback for High Performance Text Retrieval
In this paper, we investigate the use of data mining, in particular the text classification and co-training techniques, to identify more relevant passages based on a small set of labeled passages obtained from the blind feedback of a retrieval system. The data mining results are used to expand query terms and to re-estimate some of the parameters used in a probabilistic weighting function. We evaluate the data mining based feedback method on the TREC HARD data set. The results show that data mining can be successfully applied to improve the text retrieval performance. We report our experimental findings in detail.
21281863
Practical key distribution schemes for channel protection
The paper presents three key distribution schemes for channel protection. With the proposed schemes, encryption keys of the ordered programs can be distributed to the authorized subscribers efficiently and securely. In these schemes, for key updates, at most two messages are transmitted and simpler computation functions, including one-way hash function and XOR operation, are used to reduce the computation cost compared to existing solutions. With our key distribution schemes, only the authorized subscribers can decrypt the ordered programs. Thus, the service provider in a Pay-TV system can charge his subscribers according to their subscriptions and the intelligent property rights of TV programs can be protected by the proposed schemes.
18171732
Data Placement in Intermittently Available Environments
In this paper, we address the problem of data placement in a grid based multimedia environment, where the resource providers, i.e. servers, are intermittently available. The goal is to optimize the system performance by admitting maximum number of users into the system while ensuring user Quality of Service (QoS). We define and formulate various placement strategies that determine the degree of replication necessary for video objects by using a cost-based optimization procedure based on predictions of expected requests under various time-map scenarios and QoS demands. We also devise methods for dereplication of videos based on changes in popularity and server usage patterns. Our performance results indicate the benefits obtained the judicious use of dynamic placement strategies.
16825524
Resilient State Management in Large Scale Networks
This paper describes, briefly, ongoing research on resource reservation state management, including research motivations and initial design.