12861854
The Recognition of Geodetically Connected Graphs
Abstract Let G = ( V , E ) be a graph with vertex set V of size n and edge set E of size m . A vertex υ ϵ V is called a hinge vertex if the distance of any two vertices becomes longer after v is removed. A graph without hinge vertex is called a hinge-free graph. In general, a graph G is k -geodetically connected or k -GC for short if G can tolerate any k − 1 vertices failures without increasing the distance among all the remaining vertices. In this paper, we show that recognizing a graph G to be k -GC for the largest value of k can be solved in O ( nm ) time. In addition, more efficient algorithms for recognizing the k -GC property on some special graphs are presented. These include the O ( n + m ) time algorithms on strongly chordal graphs (if a strong elimination ordering is given), ptolemaic graphs, and interval graphs, and an O ( n 2 ) time algorithm on undirected path graphs (if a characteristic tree model is given). Moreover, we show that if the input graph G is not hinge-free then finding all hinge vertices of G can be solved in the same time complexity on the above classes of graphs.
45928902
An Efficient Parallel Strategy for Computing K-Terminal Reliability and Finding Most Vital Edges in 2-Trees and Partial 2-Trees
In this paper, we first develop a parallel algorithm for computingK-terminal reliability, denoted byR(GK), in 2-trees. Based on this result, we can also computeR(GK) in partial 2-trees using a method that transforms, in parallel, a given partial 2-tree into a 2-tree. Finally, we solve the problem of finding most vital edges with respect toK-terminal reliability in partial 2-trees. Our algorithms takeO(logn) time withC(m,n) processors on a CRCW PRAM, whereC(m,n) is the number of processors required to find the connected components of a graph withmedges andnvertices in logarithmic time.
3127403
An efficient parallel strategy for computing K-terminal reliability and finding most vital edge in 2-trees and partial 2-trees
The authors develop a parallel strategy to compute K-terminal reliability in 2-trees and partial 2-trees. They also solve the problem of finding the most vital edge with respect to K-terminal reliability in partial 2-trees. The algorithms take O(log n) time with C(m,n) processors on a CRCW PRAM, where C(m,n) is the number of processors required to find connected components of a graph with m edges and n vertices in logarithmic time.
10538824
Parallel Decomposition of Generalized Series-Parallel Graphs
Generalized series-parallel (GSP) graphs belong to the class of decomposable graphs which can be represented by their decomposition trees. Given a decomposition tree of a GSP graph, there are many graph-theoretic problems which can be solved efficiently. An efficient parallel algorithm for constructing a decomposition tree of a given GSP graph is presented. It takes O(log n) time with C(m, n) processors on a CRCW PRAM, where C(m, n) is the number of processors required to find connected components of a graph with in edges and n vertices in logarithmic time. Based on our algorithmic results, we also derive some properties for GSP graphs, which may be of interest in and of themselves.
29920941
Counting Clique Trees and Computing Perfect Elimination Schemes in Parallel
Abstract In a previous result, the authors showed that a clique tree of a chordal graph can be constructed in O(log n ) parallel computing time with O( n 3 ) processors on CRCW PRAM, where n is the number of nodes of the graph. In this paper, it will be shown that this result can be extended in two ways. First, we show that from the parallel clique tree constructing algorithm, we can derive an exact formula of counting clique trees of a labeled connected chordal graph. Next, we show that a perfect elimination scheme of a chordal graph can be computed in O(log n ) time with O( n 2 ) processors on CREW PRAM once a clique tree of the graph is given. This implies that a perfect elimination scheme of a chordal graph can be computed in O(log n ) time with O( n 3 ) processors on CRCW PRAM.
16976049
Efficient Broadcasting in Wormhole-Routed Multicomputers: A Network-Partitioning Approach
In this paper, a network-partitioning approach for one-to-all broadcasting on wormhole-routed networks is proposed. To broadcast a message, the scheme works in three phases. First, a number of data-distributing networks (DDNs), which can work independently, are constructed. Then the message is evenly divided into submessages, each being sent to a representative node in one DDN. Second, the submessages are broadcast on the DDNs concurrently. Finally, a number of data-collecting networks (DCNs), which can work independently too, are constructed. Then, concurrently on each DCN, the submessages are collected and combined into the original message. Our approach, especially designed for wormhole-routed networks, is conceptually similar but fundamentally very different from the traditional approach of using multiple edge-disjoint spanning trees in parallel for broadcasting in store-and-forward networks. One interesting issue is on the definition of independent DDNs and DCNs, in the sense of wormhole routing. We show how to apply this approach to tori, meshes, and hypercubes. Thorough analyses and comparisons based on different system parameters and configurations are conducted. The results do confirm the advantage of our scheme, under various system parameters and conditions, over other existing broadcasting algorithms.
641485
Mapping XML and relational schemas with Clio
Merging and coalescing data from multiple and diverse sources into different data formats continues to be an important problem in modern information systems. Schema matching (the process of matching elements of a source schema with elements of a target schema) and schema mapping (the process of creating a query that maps between two disparate schemas) are at the heart of data integration systems. We demonstrate Clio, a semi-automatic schema mapping tool developed at the IBM Almaden Research Center. In this paper, we showcase Clio's mapping engine which allows mapping to and from relational and XML schemas, and takes advantage of data constraints in order to preserve data associations.
44418101
Degree-constrained minimum spanning tree
Abstract In this paper the problem of a degree-constrained minimum spanning tree (DCMST) is defined. The problem is formulated as a linear 0–1 integer programming problem. A primal and a dual heuristic (construction) procedure and a branch-and-bound algorithm are proposed to construct a DCMST. These procedures are illustrated with a simple example. Some computational experience with these algorithms is also reported.
39997093
Performance of an Ant Colony Optimization (ACO) Algorithm on the Dynamic Load-Balanced Clustering Problem in Ad Hoc Networks
This paper examines the performance of a recently proposed ACO algorithm when applied to the problem of constructing load-balanced clusters in ad hoc networks with node mobility. Performance, in this context, is measured in terms of the magnitude of change in solution quality after nodes move, and reactivity. Reactivity refers to the number of cycles ACO takes to recover from any degradation in solution quality resulting from node movements. Empirical results on 16 problem instances of various sizes revealed a positive correlation
40677597
CHANT (CHinese ANcient Texts): a comprehensive database of all ancient Chinese texts up to 600 AD
The CHinese ANcient Texts (CHANT) database is a long-term project which began in 1988 to build up a comprehensive database of all ancient Chinese texts up to the sixth century AD. The project is near completion and the entire database, which includes both traditional and excavated materials, will be released on the CHANT Web site (www.chant.org) in mid-2002. With more than a decade of experience in establishing an electronic Chinese literary database, we have gained much insight useful to the development of similar databases in the future. We made use of the best available versions of all texts, noting variant readings in footnotes. The biggest problem we encountered is the inclusion of rare and obsolete Chinese characters. For excavated materials, we also have to incorporate a considerable number of inscriptions in the original oracle bones and bronze forms. Since we started building the database, information technology has advanced so rapidly that we had to upgrade the technical devices already in use in the database. Unification of different sub-databases is also a daunting task. To maintain our competitive edge over free online Chinese databases, we need to continue developing new databases employing the existing ones.
30879352
An Ant Colony Optimization Approach to the Degree-Constrained Minimum Spanning Tree Problem
This paper presents the application of an Ant Colony Optimization (ACO) algorithm approach for communications networks design problem. We explore the use of ACO’s for solving a network optimization problem, the degree-constrained minimum spanning tree problem (d-MST), which is a NP-Hard problem. The effectiveness of the proposed algorithm is demonstrated through two kinds of data set: structured hard (SHRD) complete graphs and misleading (M-graph) complete graphs. Empirical results show that ACO performs competitively with other approaches based on evolutionary algorithm (EA) on certain instance set problem.