The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
Uri Zwick - One of the best experts on this subject based on the ideXlab platform.
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a fully dynamic reachability algorithm for directed graphs with an almost linear update time
SIAM Journal on Computing, 2016Co-Authors: Liam Roditty, Uri ZwickAbstract:We obtain a new fully dynamic algorithm for the reachability problem in directed graphs. Our algorithm has an amortized update time of $O(m+n\log n)$ and a worst-case query time of $O(n)$, where $m$ is the current number of edges in the graph, and $n$ is the number of vertices in the graph. Each update Operation either Inserts a set of edges that touch the same vertex, or deletes an arbitrary set of edges. The algorithm is deterministic and uses fairly simple data structures. One of the ingredients used by this new algorithm may be interesting in its own right. It is a new dynamic algorithm for strong connectivity in directed graphs with an interesting ``retrospectiveness'' property. Each Insert Operation creates a new version of the graph. A delete Operation deletes edges from all versions. Strong connectivity queries can be made on each version of the graph. The algorithm handles each update in $O(m\alpha(n))$ amortized time, and each query in $O(1)$ worst-case time, where $\alpha(n)$ is a functional in...
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a fully dynamic reachability algorithm for directed graphs with an almost linear update time
Symposium on the Theory of Computing, 2004Co-Authors: Liam Roditty, Uri ZwickAbstract:We obtain a new fully dynamic algorithm for the reachability problem in directed graphs. Our algorithm has an amortized update time of O(m+n log n) and a worst-case query time of O(n), where m is the current number of edges in the graph, and n is the number of vertices in the graph. Each update Operation either Inserts a set of edges that touch the same vertex, or deletes an arbitrary set of edges. The algorithm is deterministic and uses fairly simple data structures. This is the first algorithm that breaks the O(n2) update barrier for all graphs with o(n2) edges.One of the ingredients used by this new algorithm may be interesting in its own right. It is a new dynamic algorithm for strong connectivity in directed graphs with an interesting persistency property. Each Insert Operation creates a new version of the graph. A delete Operation deletes edges from emphall versions. Strong connectivity queries can be made on each version of the graph. The algorithm handles each update in O(mα(m,n)) amortized time, and each query in O(1) time, where α(m,n) is a functional inverse of Ackermann's function appearing in the analysis of the union-find data structure. Note that the update time of O(mα(m,n)), in case of a delete Operation, is the time needed for updating all versions of the graph.
Liam Roditty - One of the best experts on this subject based on the ideXlab platform.
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a fully dynamic reachability algorithm for directed graphs with an almost linear update time
SIAM Journal on Computing, 2016Co-Authors: Liam Roditty, Uri ZwickAbstract:We obtain a new fully dynamic algorithm for the reachability problem in directed graphs. Our algorithm has an amortized update time of $O(m+n\log n)$ and a worst-case query time of $O(n)$, where $m$ is the current number of edges in the graph, and $n$ is the number of vertices in the graph. Each update Operation either Inserts a set of edges that touch the same vertex, or deletes an arbitrary set of edges. The algorithm is deterministic and uses fairly simple data structures. One of the ingredients used by this new algorithm may be interesting in its own right. It is a new dynamic algorithm for strong connectivity in directed graphs with an interesting ``retrospectiveness'' property. Each Insert Operation creates a new version of the graph. A delete Operation deletes edges from all versions. Strong connectivity queries can be made on each version of the graph. The algorithm handles each update in $O(m\alpha(n))$ amortized time, and each query in $O(1)$ worst-case time, where $\alpha(n)$ is a functional in...
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a fully dynamic reachability algorithm for directed graphs with an almost linear update time
Symposium on the Theory of Computing, 2004Co-Authors: Liam Roditty, Uri ZwickAbstract:We obtain a new fully dynamic algorithm for the reachability problem in directed graphs. Our algorithm has an amortized update time of O(m+n log n) and a worst-case query time of O(n), where m is the current number of edges in the graph, and n is the number of vertices in the graph. Each update Operation either Inserts a set of edges that touch the same vertex, or deletes an arbitrary set of edges. The algorithm is deterministic and uses fairly simple data structures. This is the first algorithm that breaks the O(n2) update barrier for all graphs with o(n2) edges.One of the ingredients used by this new algorithm may be interesting in its own right. It is a new dynamic algorithm for strong connectivity in directed graphs with an interesting persistency property. Each Insert Operation creates a new version of the graph. A delete Operation deletes edges from emphall versions. Strong connectivity queries can be made on each version of the graph. The algorithm handles each update in O(mα(m,n)) amortized time, and each query in O(1) time, where α(m,n) is a functional inverse of Ackermann's function appearing in the analysis of the union-find data structure. Note that the update time of O(mα(m,n)), in case of a delete Operation, is the time needed for updating all versions of the graph.
Janos Csirik - One of the best experts on this subject based on the ideXlab platform.
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parametric string edit distance and its application to pattern recognition
Systems Man and Cybernetics, 1995Co-Authors: Horst Bunke, Janos CsirikAbstract:A generalized version of the string matching algorithm by Wagner and Fischer (1974) is proposed. It is based on a parametrization of the edit cost. We assume constant cost for any delete and Insert Operation, but the cost for replacing a symbol is given as a parameter /spl tau/. For any two strings A and B, our algorithm computes their edit distance in terms of the parameter /spl tau/. We give the new algorithm, study some of its properties, and discuss potential applications to pattern recognition. >
Horst Bunke - One of the best experts on this subject based on the ideXlab platform.
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parametric string edit distance and its application to pattern recognition
Systems Man and Cybernetics, 1995Co-Authors: Horst Bunke, Janos CsirikAbstract:A generalized version of the string matching algorithm by Wagner and Fischer (1974) is proposed. It is based on a parametrization of the edit cost. We assume constant cost for any delete and Insert Operation, but the cost for replacing a symbol is given as a parameter /spl tau/. For any two strings A and B, our algorithm computes their edit distance in terms of the parameter /spl tau/. We give the new algorithm, study some of its properties, and discuss potential applications to pattern recognition. >
Tadao Takaoka - One of the best experts on this subject based on the ideXlab platform.
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theory of trinomial heaps
Lecture Notes in Computer Science, 2000Co-Authors: Tadao TakaokaAbstract:We design a new data structure, called a trinomial heap, which supports a decrease-key in O(1) time, and an Insert Operation and delete-min Operation in O(log n) time, both in the worst case, where n is the size of the heap. The merit of the trinomial heap is that it is conceptually simpler and easier to implement than the previously invented relaxed heap. The relaxed heap is based on binary linking, while the trinomial heap is based on ternary linking.