A graph G is a 2-tree if G = K-3, or G has a vertex v of degree 2, whose neighbours are adjacent, and G\v is a 2-tree. A characterization of the degree sequences of 2-trees is given. This characterization yields a lin...
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ISBN:
(纸本)9780898716283
A graph G is a 2-tree if G = K-3, or G has a vertex v of degree 2, whose neighbours are adjacent, and G\v is a 2-tree. A characterization of the degree sequences of 2-trees is given. This characterization yields a linear-time algorithm for recognizing and realizing degree sequences of 2-trees.
A graph G is a 2-tree if G = K-3, or G has a vertex v of degree 2, whose neighbors are adjacent, and G \ v is a 2-tree. A characterization of the degree sequences of 2-trees is given. This characterization yields a li...
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A graph G is a 2-tree if G = K-3, or G has a vertex v of degree 2, whose neighbors are adjacent, and G \ v is a 2-tree. A characterization of the degree sequences of 2-trees is given. This characterization yields a linear-time algorithm for recognizing and realizing degree sequences of 2-trees. (c) 2008 Wiley Periodicals, Inc.
The paper investigates relationship between algebraic expressions and graphs. Our intention is to simplify graph expressions and eventually find their shortest representations. We prove the decomposition lemma which a...
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We propose a structured multisignature scheme which is based on a modified ElGamal signature scheme and analyze its security. The structure takes into account the order of the signers. With serial structures, differen...
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ISBN:
(纸本)3540669671
We propose a structured multisignature scheme which is based on a modified ElGamal signature scheme and analyze its security. The structure takes into account the order of the signers. With serial structures, different signing orders produce different multisignatures. In contrast, with parallel structures the multisignatures are independent of the signing order. Our structured multisignatures can deal with structures which are composed of serial and parallel signing orders. We give reductions for the security of the proposed scheme, and for the specified order of the signers in the serial and mixed cases.
The paper investigates relationship between algebraic expressions and labeled graphs. We consider directed grid graphs having m rows and n columns. Our intent is to simplify the expressions of these graphs. With that ...
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A series-parallel graph is a graph that does not contain a complete graph with four vertices as a minor. An explicit formula for the number of labeled series-parallel tricyclic graphs with a given number of vertices i...
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Topological sorting is, given with a directed acyclic graph G = (V, E), to find a total ordering of the vertices such that if (u, v) is an element of E then u is ordered before v. Instead of topological sorting, we ar...
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Topological sorting is, given with a directed acyclic graph G = (V, E), to find a total ordering of the vertices such that if (u, v) is an element of E then u is ordered before v. Instead of topological sorting, we are interested in how many total orderings exist in a given directed acyclic graph. We call such a total ordering as legal sequence and the problem of finding total number of legal sequences as legal sequence number problem. In this paper, we firstly give necessary definitions and known results obtained in our previous research. Then we give a method how to obtain legal sequence number for a class of directed acyclic graphs, extended 2-b-SPGs. Finally we discuss the complexity of legal sequence number problem for extended 2-b-SPGs.
Assume that each vertex of a graph G is assigned a constant number q of nonnegative integer weights, and that q pairs of nonnegative integers l(i) and u(i), 1 <= i <= q, are given. One wishes to partition G into...
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Assume that each vertex of a graph G is assigned a constant number q of nonnegative integer weights, and that q pairs of nonnegative integers l(i) and u(i), 1 <= i <= q, are given. One wishes to partition G into connected components by deleting edges from G so that the total i-th weights of all vertices in each component is at least li and at most ui for each index i, 1 <= i <= q. The problem of finding such a "uniform" partition is NP-hard for series-parallel graphs, and is strongly NP-hard for general graphs even for q = 1. In this paper we show that the problem and many variants can be solved in pseudo-polynomial time for series-parallel graphs and partial k-trees, that is, graphs with bounded tree-width.
A pair of non-adjacent edges is said to be separated in a circular ordering of vertices, if the endpoints of the two edges do not alternate in the ordering. The circular separation dimension of a graph G, denoted by p...
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A pair of non-adjacent edges is said to be separated in a circular ordering of vertices, if the endpoints of the two edges do not alternate in the ordering. The circular separation dimension of a graph G, denoted by pi degrees (G), is the minimum number of circular orderings of the vertices of G such that every pair of non-adjacent edges is separated in at least one of the circular orderings. This notion is introduced by Loeb and West in their recent paper. In this article, we consider two subclasses of planar graphs, namely 2-outerplanar graphs and series-parallel graphs. A 2-outerplanar graph has a planar embedding such that the subgraph obtained by removal of the vertices of the exterior face is outerplanar. We prove that if G is 2-outerplanar then pi degrees (G) = 2. We also prove that if G is a series-parallel graph then pi degrees (G) <= 2.
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