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
1145137
Agent-assisted collaborative concept map
Merlin is a collaborative concept map that enables students to discuss their ideas. The agent in Merlin aims to monitor the students' content of discussion in order to provide context-sensitive help. Keywords in the students' discussion in a chat box are compared to the knowledge domain and appropriate support material is adapted to the student model. Instructional media is generated using design patterns.
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.
13477825
A HYBRID GENETIC ALGORITHM FOR OPTICAL ORTHOGONAL CODE CONSTRUCTION
Optical orthogonal codes (OOCs) are used to uniquely identify stations within an optical code division multiple access (CDMA) local area network (LAN). Previous efforts in constructing OOCs have focused on the use of deterministic techniques, which relied heavily on the use of Galois fields. These techniques severely restrict the availability of the resulting OOCs. This paper considers an evolutionary approach by proposing a hybrid genetic algorithm (hGA) as a flexible technique to construct OOCs. This hGA uses the simulated annealing (SA) method to generate its initial population. The effectiveness of the proposed hGA for OOC construction is demonstrated in two stages. First, we show that the SA-generated initial population is better than the randomly generated initial population in terms of fitness. Due to this, the hGA is able to converge on average two times faster compared to the use of the GA-only scheme. Second, we compare the code availability and performance of the hGA-constructed OOCs (hGA OOCs) against that of three other OOCs. Through these comparisons, we show why the proposed hGA is a more flexible technique for constructing OOCs with higher availability and better performance.
7074686
Efficient parallel algorithms on distance-hereditary graphs
We present efficient parallel algorithms for finding a minimum weighted connected dominating set, a minimum weighted Steiner tree for a distance-hereditary graph which take O(log n) time using O(n+m) processors on a CRCW PRAM, where n and m are the number of vertices and edges of a given graph, respectively. We also find a maximum weighted clique of a distance-hereditary graph in O(log/sup 2/ n) time using O(n+m) processors on a CREW PRAM.
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.
5965550
An extension of the bipartite weighted matching problem
Abstract An extension of the bipartite weighted matching problem is considered in this paper. Given the weight of each edge and the penalty of each vertex, the matching goal is to find a matching such that the sum of the weights of matching edges plus the penalties of unmatched vertices is minimum. In this paper, a reduction algorithm is proposed, which is found to be capable of reducing the matching problem to the assignment problem.
34381900
Using spatial warning signals to capture a driver's visual attention
This study was designed to assess the potential benefits of using spatial auditory or vibrotactile warning signals in the domain of driving performance, using a simulated driving task. Across six experiments, participants had to monitor a rapidly presented stream of distractor letters for occasional target digits (simulating an attention-demanding visual task, such as driving). Whenever participants heard an auditory cue (E1-E4) or felt a vibration (E5-E6), they had to check the front and the rearview mirror for the rapid approach of a car from in front or behind and respond accordingly (either by accelerating or braking). The efficacy of various auditory and vibrotactile warning signals in directing a participant's visual attention to the correct environmental position was compared (see Table 1). The results demonstrate the potential utility of semantically-meaningful or spatial auditory, and/or vibrotactile warning signals in interface design for directing a driver's, or other interface-operator's, visual attention to time-critical events or information.
10116161
Graph Searching on Chordal Graphs
Two variations of the graph searching problem, edge searching and node searching, are studied on several classes of chordal graphs, which include split graphs, interval graphs and k-starlike graphs.