8865105
Edge and node searching problems on trees
In this paper, we show that there is a natural correspondence between a tree's edge-search strategy and its node-search strategy. By doing so, we simplify the previous linear time algorithm for determining the edge-search number of a tree, and improve the running time of a previous algorithm for constructing an edge-search strategy (or plan) for a tree containing n vertices from O(n log n) to O(n) time.
44408883
Hamiltonian-laceability of star graphs
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.
1980858
Edge and Node Searching Problems on Trees
In this paper, we show that there is a natural correspondence between a tree's edge-search strategy and its node-search strategy. By doing so, we simplify the previous linear time algorithm for determining the edge-search number of a tree, and improve the running time of a previous algorithm for constructing an edge-search strategy (or plan) for a tree containing n vertices from O(n log n) to O(n) time.
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.
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.
8958554
Nested mappings: schema mapping reloaded
Many problems in information integration rely on specifications, called schema mappings, that model the relationships between schemas. Schema mappings for both relational and nested data are well-known. In this work, we present a new formalism for schema mapping that extends these existing formalisms in two significant ways. First, our nested mappings allow for nesting and correlation of mappings. This results in a natural programming paradigm that often yields more accurate specifications. In particular, we show that nested mappings can naturally preserve correlations among data that existing mapping formalisms cannot. We also show that using nested mappings for purposes of exchanging data from a source to a target will result in less redundancy in the target data. The second extension to the mapping formalism is the ability to express, in a declarative way, grouping and data merging semantics. This semantics can be easily changed and customized to the integration task at hand. We present a new algorithm for the automatic generation of nested mappings from schema matchings (that is, simple element-to-element correspondences between schemas). We have implemented this algorithm, along with algorithms for the generation of transformation queries (e.g., XQuery) based on the nested mapping specification. We show that the generation algorithms scale well to large, highly nested schemas. We also show that using nested mappings in data exchange can drastically reduce the execution cost of producing a target instance, particularly over large data sources, and can also dramatically improve the quality of the generated data.
12331697
The Clio project: managing heterogeneity
Clio is a system for managing and facilitating the complex tasks of heterogeneous data transformation and integration. In Clio, we have collected together a powerful set of data management techniques that have proven invaluable in tackling these difficult problems. In this paper, we present the underlying themes of our approach and present a brief case study.
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.
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.
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.