Within the broad ambit of algorithm design, the study of dynamic graph algorithms continues to be a thriving area of research. Commensurate with this interest is an extensive literature on the topic. Not surprisingly,...
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Within the broad ambit of algorithm design, the study of dynamic graph algorithms continues to be a thriving area of research. Commensurate with this interest is an extensive literature on the topic. Not surprisingly, dynamicalgorithms for all varieties of shortest path problems, in view of their practical importance, occupy a preeminent position. Relevant to this paper are fully dynamicalgorithms for chordal graphs. Surprisingly, to the best of our knowledge, there seems to be no reported results for the problem of dynamicalgorithms for strongly chordal graphs. To redress this gap, in this paper, we propose a semi-dynamic algorithm for edge-deletions and a semi-dynamic algorithm for edge-insertions in a strongly chordal graph, G. The query complexity of an edge-deletion is O(d(u)(2)d(v)(2)), where d(u) and d(v) are the degrees of the vertices u and v of the candidate edge {u,v}, while the query complexity of an edge-insertion is O(n(2)), where n is the number of vertices of G.
Given a directed graph G, a source vertex s and shortest path tree (SPT). T(s) rooted at 8 in G, the dynamic shortest path problem is to find the new SPT, T'(s) in G from T(s) when update(s) on edge weight(s) are ...
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ISBN:
(纸本)9783642240362;9783642240379
Given a directed graph G, a source vertex s and shortest path tree (SPT). T(s) rooted at 8 in G, the dynamic shortest path problem is to find the new SPT, T'(s) in G from T(s) when update(s) on edge weight(s) are performed. Previous works focus either on single edge weight update at a time or, process a set of updates together with the constraint that edge weights remain positive. In this paper we propose two semi-dynamic algorithms (one for increase only and the other for decrease only case) for maintaining SPT in a directed graph, even when some of edge weights assume negative values. Our algorithms process multiple edge weight updates simultaneously and also able to detect presence of negative weight cycle if introduced during update, to assert that no real SPT exists. From experiments conducted, we observe that dynamicalgorithms perform better than the static algorithm when the percentage of updated edges is smaller than a certain threshold.
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