enumeration of spanning trees of an undirected graph is one of the graph problems that has received much attention in the literature. In this paper a new enumeration algorithm based on the idea of contractions of the ...
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enumeration of spanning trees of an undirected graph is one of the graph problems that has received much attention in the literature. In this paper a new enumeration algorithm based on the idea of contractions of the graph is presented. The worst-case time complexity of the algorithm isO(n+m+nt) wheren is the number of vertices,m the number of edges, andt the number of spanning trees in the graph. The worst-case space complexity of the algorithm isO(n 2). Computational analysis indicates that the algorithm requires less computation time than any other of the previously best-known algorithms.
Extensive-form games with perfect information admit at least one Nash equilibrium. The backward induction algorithm identifies in linear time a Nash equilibrium of the game, called subgame perfect. We introduce an ext...
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The security of lattice-based cryptosystems is generally based on the hardness of the Shortest Vector Problem (SVP). There are two common categories of lattice algorithms to solve SVP: search algorithms and reduction ...
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ISBN:
(纸本)9783031088964;9783031088957
The security of lattice-based cryptosystems is generally based on the hardness of the Shortest Vector Problem (SVP). There are two common categories of lattice algorithms to solve SVP: search algorithms and reduction algorithms. The original enumeration algorithm (ENUM) is one of the former algorithms which run in exponential time due to the exhaustive search. Further, ENUM is used as a subroutine for the BKZ algorithm, which is one of the most practical reduction algorithms. It is a critical issue to reduce the computational complexity of ENUM. In this paper, first, we improve the mechanism in the so-called reordering method proposed by Wang in ACISP 2018. We call this improvement Primal Projective Reordering (PPR) method which permutates the projected vectors by decreasing norms;therefore it performs better to reduce the number of search nodes in ENUM. Then, we propose a Dual Projective Reordering (DPR) method permutating the projected vectors in its dual lattice. In addition, we propose a condition to decide whether the reordering method should be adopted or not. Preliminary experimental results show that our proposed reordering methods can successfully reduce the number of ENUM search nodes comparing to the predecessor, e.g., PPR reduces around 9.6% on average in 30-dimensional random lattices, and DPR reduces around 32.8% on average in 45-dimensional random lattices. Moreover, our simulation shows that the higher the lattice dimension, the more the proposed reordering method can reduce ENUM search nodes.
A compatible Euler trail (tour) in an edge-colored graph is an Euler trail (tour) in which each two edges traversed consecutively along the Euler trail (tour) have distinct colors. In this paper, we show that the prob...
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A compatible Euler trail (tour) in an edge-colored graph is an Euler trail (tour) in which each two edges traversed consecutively along the Euler trail (tour) have distinct colors. In this paper, we show that the problem of counting compatible Euler trails in edge-colored graphs is #P-complete, and develop O(m N) time algorithms for enumerating compatible Euler trails (tours) in edge-colored graphs with m edges and N compatible Euler trails (tours). It is worth mentioning that our algorithms can run in O(N) time when there is no vertex v with degree 4 and maximum monochromatic degree 2.
For a linear structure subjected to the unilateral contact condition with a fixed obstacle, we refer to a non-trivial equilibrium state as a wedged configuration. Finding a wedged configuration is called a wedging pro...
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For a linear structure subjected to the unilateral contact condition with a fixed obstacle, we refer to a non-trivial equilibrium state as a wedged configuration. Finding a wedged configuration is called a wedging problem. This paper discusses theoretical properties of solution set of the finite-dimensional wedging problem with the Coulomb friction, and presents numerical methods for computing all the wedged configurations. We propose algorithms for enumerating all the finitely many representative solutions, with which we can completely describe the solution set of the wedging problem. There exists a positive critical friction coefficient defined as the minimum value of friction coefficient with which at least one wedged configuration exists. We also propose an algorithm for computing the critical friction coefficient, which is based on the bisection method and the second-order cone program. (c) 2009 Elsevier B.V. All rights reserved.
A ladder lottery, known as "Amidakuji" in Japan, is a common way to choose a permutation randomly. A ladder lottery L corresponding to a given permutation pi is optimal if L has the minimum number of horizon...
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A ladder lottery, known as "Amidakuji" in Japan, is a common way to choose a permutation randomly. A ladder lottery L corresponding to a given permutation pi is optimal if L has the minimum number of horizontal lines among the ladder lotteries corresponding to pi. In this paper we show that for any two optimal ladder lotteries L-1 and L-2 of a permutation, there exists a sequence of local modifications which transforms L-1 into L-2. We also give an algorithm to enumerate all optimal ladder lotteries of a given permutation. By setting pi = (n, n - 1,..., 1), the algorithm enumerates all arrangements of n pseudolines efficiently. By implementing the algorithm we compute the number of arrangements of n pseudolines for each n <= 11. (C) 2010 Elsevier B.V. All rights reserved.
A dominating set D of a graph G is a set of vertices such that any vertex in G is in D or its neighbor is in D. enumeration of minimal dominating sets in a graph is one of the central problems in enumeration study sin...
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A dominating set D of a graph G is a set of vertices such that any vertex in G is in D or its neighbor is in D. enumeration of minimal dominating sets in a graph is one of the central problems in enumeration study since enumeration of minimal dominating sets corresponds to the enumeration of minimal hypergraph transversals. The output-polynomial time enumeration of minimal hypergraph transversals is an interesting open problem. On the other hand, enumeration of dominating sets including non-minimal ones has not been received much attention. In this paper, we address enumeration problems for dominating sets from sparse graphs which are degenerate graphs and graphs with large girth, and we propose two algorithms for solving the problems. The first algorithm enumerates all the dominating sets for a k-degenerate graph in O (k) time per solution using O (n + m) space, where n and m are respectively the number of vertices and edges in an input graph. That is, the algorithm is optimal for graphs with constant degeneracy such as trees, planar graphs, H-minor free graphs with some fixed H. The second algorithm enumerates all the dominating sets in constant time per solution for input graphs with girth at least nine. (C) 2021 Elsevier B.V. All rights reserved.
By the motivation to discover patterns in massive structured data in the form of graphs and trees, we study a special case of the k-subtree enumeration problem with a tree of n nodes as an input graph, which is origin...
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By the motivation to discover patterns in massive structured data in the form of graphs and trees, we study a special case of the k-subtree enumeration problem with a tree of n nodes as an input graph, which is originally introduced by (Ferreira, Grossi, and Rizzi, ESA' 11, 275-286, 2011) for general graphs. Based on reverse search technique (Avis and Fukuda, Discrete Appl. Math., vol.65, pp.21-46, 1996), we present the first constant delay enumeration algorithm that lists all k-subtrees of an input rooted tree in O(1) worst-case time per subtree. This result improves on the straightforward application of Ferreira et al's algorithm with O(k) amortized time per subtree when an input is restricted to tree. Finally, we discuss an application of our algorithm to a modification of the graph motif problem for trees.
In this study, we address a problem pertaining to the induced matching enumeration. An edge set M is an induced matching of a graph G = (V;E). The enumeration of matchings has been widely studied in literature;however...
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In this study, we address a problem pertaining to the induced matching enumeration. An edge set M is an induced matching of a graph G = (V;E). The enumeration of matchings has been widely studied in literature;however, there few studies on induced matching. A straightforward algorithm takes O(Delta(2)) time for each solution that is coming from the time to generate a subproblem, where Delta is the maximum degree in an input graph. To generate a subproblem, an algorithm picks up an edge e and generates two graphs, the one is obtained by removing e from G, the other is obtained by removing e, adjacent edge to e, and edges adjacent to adjacent edge of e. Since this operation needs O (Delta(2)) time, a straightforward algorithm enumerates all induced matchings in O (Delta(2)) time per solution. We investigated local structures that enable us to generate subproblems within a short time and proved that the time complexity will be O (1) if the input graph is C-4-free. A graph is C-4-free if and only if none of its subgraphs have a cycle of length four.
In this paper, we consider enumeration problems for edge-distinct and vertex-distinct Eulerian trails. Two Eulerian trails are said to be edge-distinctif the edge sequences are not identical, and they are said to be v...
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In this paper, we consider enumeration problems for edge-distinct and vertex-distinct Eulerian trails. Two Eulerian trails are said to be edge-distinctif the edge sequences are not identical, and they are said to be vertex-distinctif the vertex sequences are not identical. To solve these problems, we propose optimal enumeration algorithms that run in O(N+ m) total time, where Nis the number of solutions and mis the number of edges in an input connected graph. The proposed algorithms are based on the reverse search technique introduced by [Avis and Fukuda, DAM 1996], and the push-out amortization technique introduced by [Uno, WADS 2015]. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).
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