Browsing by Author "Liptak, Laszlo"

Now showing 1 - 5 of 5

4-ordered-Hamiltonian problems of the generalized Petersen graph GP(n, 4)
(2013-02-01)
Hung, Chun-Nan
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Lu, David
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Jia, Randy
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Lin, Cheng-Kuan
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Liptak, Laszlo
A graph G is k-ordered if for every sequence of k distinct vertices of G, there exists a cycle in G containing these k vertices in the specified order. It is k-ordered-Hamiltonian if, in addition, the required cycle is a Hamiltonian cycle in G. The question of the existence of an infinite class of 3-regular 4-ordered-Hamiltonian graphs was posed in Ng and Schultz in 1997 [2]. At the time, the only known examples of such graphs were K-4 and K-3,K-3. Some progress was made by Meszaros in 2008 [21] when the Petersen graph was found to be 4-ordered and the Heawood graph was proved to be 4-ordered-Hamiltonian; moreover, an infinite class of 3-regular 4-ordered graphs was found. In 2010, a subclass of the generalized Petersen graphs was shown to be 4-ordered in Hsu et al. [9], with an infinite subset of this subclass being 4-ordered-Hamiltonian, thus answering the open question. However, these graphs are bipartite. In this paper we extend the result to another subclass of the generalized Petersen graphs. In particular, we find the first class of infinite non-bipartite graphs that are both 4-ordered-Hamiltonian and 4-ordered-Hamiltonian-connected, which can be seen as a solution to an extension of the question posted in Ng and Schultz in 1997 [2]. (A graph G is k-ordered-Hamiltonian-connected if for every sequence of k distinct vertices a(1), a(2),..., a(k) of G, there exists a Hamiltonian path in G from a(1) to a(k) where these k vertices appear in the specified order.) (C) 2012 Elsevier Ltd. All rights reserved.
Component connectivity of the hypercubes
(2012)
Hsu, Lih-Hsing
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Cheng, Eddie
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Liptak, Laszlo
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Tan, Jimmy J. M.
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Lin, Cheng-Kuan
The r-component connectivity kappa(r)(G) of the non- complete graph G is the minimum number of vertices whose deletion results in a graph with at least r components. So, kappa(2) is the usual connectivity. In this paper, we determine the r-component connectivity of the hypercube Q(n) for r = 2, 3, ..., n + 1, and we classify all the corresponding optimal solutions.
Conditional Fault Hamiltonicity of the Star Graph
(2014-01-01)
Lin, Cheng-Kuan
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Tan, Jimmy J. M.
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Hsu, Lih-Hsing
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Cheng, Eddie
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Liptak, Laszlo
Fault tolerance is an important property on network performance. A graph G is k-edge-fault conditional hamiltonian if G - F is hamiltonian for every F subset of E(G) with vertical bar F vertical bar <= k and delta(G - F) >= 2. In this paper we show that for n >= 4 the n-dimensional star graph S-n is (3n - 10)-edge-fault conditional hamiltonian.
CONDITIONAL MATCHING PRECLUSION FOR THE STAR GRAPHS
(2015-04-01)
Cheng, Eddie
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Liptak, Laszlo
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Hsu, Lih-Hsing
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Tan, Jimmy J. M.
;
Lin, Cheng-Kuan
The matching preclusion number of a graph is the minimum number of edges whose deletion results in a graph that has neither perfect matchings nor almost-perfect matchings. For many interconnection networks, the optimal sets are precisely those incident to a single vertex. Recently, the conditional matching preclusion number of a graph was introduced to look for obstruction sets beyond those incident to a single vertex. It is defined to be the minimum number of edges whose deletion results in a graph with no isolated vertices that has neither perfect matchings nor almost-perfect matchings. In this paper, we find this number and classify all optimal sets for the star graphs, one of the most popular interconnection networks.
Solution to an open problem on 4-ordered Hamiltonian graphs
(2012-08-06)
Hsu, Lih-Hsing
;
Tan, Jimmy J. M.
;
Cheng, Eddie
;
Liptak, Laszlo
;
Lin, Cheng-Kuan
A graph G is k-ordered if for any sequence of k distinct vertices of G, there exists a cycle in G containing these k vertices in the specified order. It is k-ordered Hamiltonian if, in addition, the required cycle is Hamiltonian. The question of the existence of an infinite class of 3-regular 4-ordered Hamiltonian graphs was posed in Ng and Schultz (1997) [10]. At the time, the only known examples were K-4 and K-3.3. Some progress was made in Meszaros (2008) [9] when the Peterson graph was found to be 4-ordered and the Heawood graph was proved to be 4-ordered Hamiltonian: moreover an infinite class of 3-regular 4-ordered graphs was found. In this paper we show that a subclass of generalized Petersen graphs are 4-ordered and give a complete classification for which of these graphs are 4-ordered Hamiltonian. In particular, this answers the open question regarding the existence of an infinite class of 3-regular 4-ordered Hamiltonian graphs. Moreover, a number of results related to other open problems are presented. (C) 2012 Elsevier B.V. All rights reserved.