38028770
On The Trees Whose 2-Step Competition Numbers Are Two
24157798
Domination graphs of regular tournaments
Abstract Let ℘ ∗ (m,n) denote the set of all graphs that are the union of m even paths and n nontrivial odd paths, and ℘(m,n) denote the set of all graphs that are the union of m even paths and n odd paths. In this paper, we show that if G is the domination graph of a regular tournament then G∈℘(m,n) or G is an odd cycle. Also we give a necessary and sufficient condition for G∈℘ ∗ (m,n) to be the domination graph of a regular tournament. Constructions used in this paper will provide insight into the structure of a large class of regular tournaments.
14022405
The m-step competition graph of a digraph
The competition graph of a digraph was introduced by Cohen in 1968 associated with the study of ecosystems. Since then, the competition graph has been widely studied and many variations have been introduced. In this paper, we define and study the m-step competition graph of a digraph which is another generalization of competition graph.
1778793
The competition number of a graph having exactly one hole
Let D be an acyclic digraph. The competition graph of D has the same set of vertices as D and an edge between vertices u and v if and only if there is a vertex x in D such that (u,x) and (v,x) are arcs of D. The competition number of a graph G, denoted by k(G), is the smallest number k such that G together with k isolated vertices is the competition graph of an acyclic digraph. In this paper, we show that the competition number of a graph having exactly one chordless cycle of length at least 4 is at most two. We also give a large family of such graphs whose competition numbers are less than or equal to one.
5634674
A class of acyclic digraphs with interval competition graphs
Let D be an acyclic digraph. The competition graph of D has the same set of vertices as D and an edge between vertices u and v if and only if there is a vertex x in D such that (u, x) and (v, x) are arcs of D. In this paper, we show that the competition graphs of doubly partial orders are interval graphs. We also show that an interval graph together with enough isolated vertices is the competition graph of a doubly partial order. Finally, we introduce a new notion called the doubly partial order competition number of an interval graph and present some open questions.
11159214
The impacts of Delphi communication structure on small and medium sized asynchronous groups: preliminary results
Communication structure is a way of improving the effectiveness of group communications by coordinating group members' individual efforts. This study investigates the use of Delphi, a communication structure which has been widely used to collect ideas and opinions from geographically dispersed experts. A new approach in Delphi implementation using asynchronous computer-mediated communication (CMC) is developed. A 2X2 controlled experiment investigates the effect of Delphi structure on small-sized (5-6 members) and medium-sized (10-12 members) asynchronous CMC groups. The group task is to describe the potential applications and impacts of pervasive devices that can track the location of individuals. Preliminary results indicate that the Delphi structure does result in more unique ideas per person than the unstructured condition.
15537544
Load sharing and session preservation with multiple mobile routers for large scale network mobility
By means of network mobility (NEMO) support, users can organize their various communication devices into a network, called a mobile network. In a mobile network, the mobile router provides the connectivity to the Internet and mobility management transparency for the rest of the mobile nodes in the mobile network. So, it is important for the mobile router to assure reliable communications and a high data rate for the group of nodes behind it. In support of broadband wireless communications, the use of multiple mobile routers would allow the transfer of large volumes of data to a group of mobile nodes. This paper addresses the protocol issues arising from the use of multiple mobile routers, and analyzes the influence of mobility on load sharing and session preservation when there are multiple mobile routers. Simulation results with different configurations show that session preservation and load sharing schemes are influenced by application mobility behavior and wireless access technologies.
5814506
Efficient Monitoring Algorithm for Fast News Alerts
Recently, there has been a dramatic increase in the use of XML data to deliver information over the Web. Personal Weblogs, news Web sites, and discussion forums are now publishing RSS feeds for their subscribers to retrieve new postings. As the popularity of personal Weblogs and RSS feeds grows rapidly, RSS aggregation services and blog search engines have appeared, which try to provide a central access point for simpler access and discovery of new content from a large number of diverse RSS sources. In this paper, we study how the RSS aggregation services should monitor the data sources to retrieve new content quickly using minimal resources and to provide its subscribers with fast news alerts. We believe that the change characteristics of RSS sources and the general user access behavior pose distinct requirements that make this task significantly different from the traditional index refresh problem for Web search engines. Our studies on a collection of 10,000 RSS feeds reveal some general characteristics of the RSS feeds and show that, with proper resource allocation and scheduling, the RSS aggregator provides news alerts significantly faster than the best existing approach.
22820549
Mobility-Aware Mobile Router Selection and Address Management for IPv6 Network Mobility
Network mobility (NEMO) extends IP mobility to moving networks, which are groups of nodes that often constitute a subnet of a mobile router (MR). To realize this collective mobility, there are a number of important issues such as addressing and multihoming. With the proliferation of mobile nodes connected to the Internet, the efficient allocation/deallocation of addresses is becoming a vital requirement. We propose a collaborative address management scheme for network mobility, where the home DHCPv6 agent of a mobile network performs prefix delegation, while the mobile DHCPv6 agent (in the mobile network) allocates the IPv6 address to each mobile node. Also, network mobility with multiple MRs is taken into consideration. To provide a mobile network that has multiple MRs with robust Internet connectivity, we propose mobility-aware mobile router selection schemes. The concept of “mobility awareness” refers to the capability of a moving network in a vehicle (e.g., a train) to pinpoint the most stable Internet connectivity, by choosing the mobile router based on the vehicle’s movement pattern. The simulation shows that the proposed scheme outperforms a round-robin mobile router selection scheme in terms of the amount of carried traffic.