Hisao Tamaki | Meiji University (original) (raw)

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Papers by Hisao Tamaki

Research paper thumbnail of Old resolution with resolution

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Research paper thumbnail of Positive-instance driven dynamic programming for treewidth

Journal of Combinatorial Optimization

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Research paper thumbnail of Route-Enabling Graph Orientation Problems

Proceedings of the 20th International Symposium on Algorithms and Computation, 2009

ABSTRACT Given an undirected and edge-weighted graph G together with a set of ordered vertex-pair... more ABSTRACT Given an undirected and edge-weighted graph G together with a set of ordered vertex-pairs, called st-pairs, we consider the problems of finding an orientation of all edges in G: min-sum orientation is to minimize the sum of the shortest directed distances between all st-pairs; and min-max orientation is to minimize the maximum shortest directed distance among all st-pairs. In this paper, we first show that both problems are strongly NP-hard for planar graphs even if all edge-weights are identical, and that both problems can be solved in polynomial time for cycles. We then consider the problems restricted to cacti, which form a graph class that contains trees and cycles but is a subclass of planar graphs. Then, min-sum orientation is solvable in polynomial time, whereas min-max orientation remains NP-hard even for two st-pairs. However, based on LP-relaxation, we present a polynomial-time 2-approximation algorithm for min-max orientation. Finally, we give a fully polynomial-time approximation scheme (FPTAS) for min-max orientation on cacti if the number of st-pairs is a fixed constant.

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Research paper thumbnail of Fast Deflection Routing for Packets and Worms (Extended Summary)

Podc, 1993

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Research paper thumbnail of Covering points in the plane by

Stoc, 1997

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Research paper thumbnail of Algorithms for the Maximum Subarray Problem Based on Matrix Multiplication

Interdisciplinary Information Sciences, 2000

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Research paper thumbnail of A Transformation System for Logic Programs which Preserves Equivalence

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Research paper thumbnail of MAX/C on Sakai - A Web-based C-Programming Course

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Research paper thumbnail of Transformational Logic Program Synthesis

Fgcs, 1984

ABSTRACT

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Research paper thumbnail of A Characterization of Planar Graphs by Pseudo-Line Arrangements

Algorithmica, 2002

ABSTRACT

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Research paper thumbnail of Approximation Algorithms for Geometric Optimization Problems(Special Issue on Algorithm Engineering : Surveys)

Ieice Transactions on Information and Systems, Mar 25, 2000

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Research paper thumbnail of A generalized correctness proof of the unfold/ fold logic program transformation

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Research paper thumbnail of A directed path-decomposition approach to exactly identifying attractors of boolean networks

2010 10th International Symposium on Communications and Information Technologies, 2010

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Research paper thumbnail of Robust bounded-degree networks with small diameters

Proceedings of the fourth annual ACM symposium on Parallel algorithms and architectures - SPAA '92, 1992

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Research paper thumbnail of A Linear Time Heuristic for the Branch-Decomposition of Planar Graphs

Lecture Notes in Computer Science, 2003

Let G be a biconnected planar graph given together with its planar drawing. Let VF(G) denote the ... more Let G be a biconnected planar graph given together with its planar drawing. Let VF(G) denote the bipartite graph on the sets of vertices and of faces of G such that each of its edges represents an incidence in G between a face and a vertex. Let α G denote the maximum distance in VF(G) from the outerface of G.

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Research paper thumbnail of A Polynomial Time Algorithm for Bounded Directed Pathwidth

Lecture Notes in Computer Science, 2011

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Research paper thumbnail of OLDT Resolution with Tabling

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Research paper thumbnail of On the Pathwidth of Almost Semicomplete Digraphs

Lecture Notes in Computer Science, 2015

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Research paper thumbnail of Algorithms for the Maximum Subarray Problem Based on Matrix Multiplication

Interdisciplinary Information Sciences, 2000

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Research paper thumbnail of Unfold/fold transformations of logic programs

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Research paper thumbnail of Old resolution with resolution

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Research paper thumbnail of Positive-instance driven dynamic programming for treewidth

Journal of Combinatorial Optimization

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Research paper thumbnail of Route-Enabling Graph Orientation Problems

Proceedings of the 20th International Symposium on Algorithms and Computation, 2009

ABSTRACT Given an undirected and edge-weighted graph G together with a set of ordered vertex-pair... more ABSTRACT Given an undirected and edge-weighted graph G together with a set of ordered vertex-pairs, called st-pairs, we consider the problems of finding an orientation of all edges in G: min-sum orientation is to minimize the sum of the shortest directed distances between all st-pairs; and min-max orientation is to minimize the maximum shortest directed distance among all st-pairs. In this paper, we first show that both problems are strongly NP-hard for planar graphs even if all edge-weights are identical, and that both problems can be solved in polynomial time for cycles. We then consider the problems restricted to cacti, which form a graph class that contains trees and cycles but is a subclass of planar graphs. Then, min-sum orientation is solvable in polynomial time, whereas min-max orientation remains NP-hard even for two st-pairs. However, based on LP-relaxation, we present a polynomial-time 2-approximation algorithm for min-max orientation. Finally, we give a fully polynomial-time approximation scheme (FPTAS) for min-max orientation on cacti if the number of st-pairs is a fixed constant.

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Research paper thumbnail of Fast Deflection Routing for Packets and Worms (Extended Summary)

Podc, 1993

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Research paper thumbnail of Covering points in the plane by

Stoc, 1997

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Research paper thumbnail of Algorithms for the Maximum Subarray Problem Based on Matrix Multiplication

Interdisciplinary Information Sciences, 2000

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Research paper thumbnail of A Transformation System for Logic Programs which Preserves Equivalence

Bookmarks Related papers MentionsView impact

Research paper thumbnail of MAX/C on Sakai - A Web-based C-Programming Course

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Transformational Logic Program Synthesis

Fgcs, 1984

ABSTRACT

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Research paper thumbnail of A Characterization of Planar Graphs by Pseudo-Line Arrangements

Algorithmica, 2002

ABSTRACT

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Research paper thumbnail of Approximation Algorithms for Geometric Optimization Problems(Special Issue on Algorithm Engineering : Surveys)

Ieice Transactions on Information and Systems, Mar 25, 2000

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Research paper thumbnail of A generalized correctness proof of the unfold/ fold logic program transformation

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A directed path-decomposition approach to exactly identifying attractors of boolean networks

2010 10th International Symposium on Communications and Information Technologies, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Robust bounded-degree networks with small diameters

Proceedings of the fourth annual ACM symposium on Parallel algorithms and architectures - SPAA '92, 1992

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Linear Time Heuristic for the Branch-Decomposition of Planar Graphs

Lecture Notes in Computer Science, 2003

Let G be a biconnected planar graph given together with its planar drawing. Let VF(G) denote the ... more Let G be a biconnected planar graph given together with its planar drawing. Let VF(G) denote the bipartite graph on the sets of vertices and of faces of G such that each of its edges represents an incidence in G between a face and a vertex. Let α G denote the maximum distance in VF(G) from the outerface of G.

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Research paper thumbnail of A Polynomial Time Algorithm for Bounded Directed Pathwidth

Lecture Notes in Computer Science, 2011

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Research paper thumbnail of OLDT Resolution with Tabling

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Research paper thumbnail of On the Pathwidth of Almost Semicomplete Digraphs

Lecture Notes in Computer Science, 2015

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Research paper thumbnail of Algorithms for the Maximum Subarray Problem Based on Matrix Multiplication

Interdisciplinary Information Sciences, 2000

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Research paper thumbnail of Unfold/fold transformations of logic programs

Bookmarks Related papers MentionsView impact

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