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41.
Let G be a quadripartite graph with N vertices in each vertex class and each vertex is adjacent to at least vertices in each of the other classes. There exists an N0 such that, if N?N0, then G contains a subgraph that consists of N vertex-disjoint copies of K4. 相似文献
42.
We prove strong theorems for the local time at infinity of a nearest neighbor transient random walk. First, laws of the iterated logarithm are given for the large values of the local time. Then we investigate the length of intervals over which the walk runs through (always from left to right) without ever returning. 相似文献
43.
Endre Boros Peter L. Hammer Toshihide Ibaraki Alexander Kogan 《Mathematical Programming》1997,79(1-3):163-190
“Logical analysis of data” (LAD) is a methodology developed since the late eighties, aimed at discovering hidden structural
information in data sets. LAD was originally developed for analyzing binary data by using the theory of partially defined
Boolean functions. An extension of LAD for the analysis of numerical data sets is achieved through the process of “binarization”
consisting in the replacement of each numerical variable by binary “indicator” variables, each showing whether the value of
the original variable is above or below a certain level. Binarization was successfully applied to the analysis of a variety
of real life data sets. This paper develops the theoretical foundations of the binarization process studying the combinatorial
optimization problems related to the minimization of the number of binary variables. To provide an algorithmic framework for
the practical solution of such problems, we construct compact linear integer programming formulations of them. We develop
polynomial time algorithms for some of these minimization problems, and prove NP-hardness of others.
The authors gratefully acknowledge the partial support by the Office of Naval Research (grants N00014-92-J1375 and N00014-92-J4083). 相似文献
44.
In this paper we present an algorithm to generate all minimal 3-vertex connected spanning subgraphs of an undirected graph with n vertices and m edges in incremental polynomial time, i.e., for every K we can generate K (or all) minimal 3-vertex connected spanning subgraphs of a given graph in O(K2log(K)m2+K2m3) time, where n and m are the number of vertices and edges of the input graph, respectively. This is an improvement over what was previously available and is the same as the best known running time for generating 2-vertex connected spanning subgraphs. Our result is obtained by applying the decomposition theory of 2-vertex connected graphs to the graphs obtained from minimal 3-vertex connected graphs by removing a single edge. 相似文献
45.
A minimal blocker in a bipartite graph G is a minimal set of edges the removal of which leaves no perfect matching in G. We give an explicit characterization of the minimal blockers of a bipartite graph G. This result allows us to obtain a polynomial delay algorithm for finding all minimal blockers of a given bipartite graph. Equivalently, we obtain a polynomial delay algorithm for listing the anti‐vertices of the perfect matching polytope of G. We also provide generation algorithms for other related problems, including d‐factors in bipartite graphs, and perfect 2‐matchings in general graphs. © 2006 Wiley Periodicals, Inc. J Graph Theory 53: 209–232, 2006 相似文献
46.
Attila Vertes Ernó Kuzmann György Vértes Zoltán Szökefalvy-Nagy Endre Kótay Gábor Mezey 《Hyperfine Interactions》1988,42(1-4):1013-1016
Nickel was electrodeposited on one side and chromium on the other side of a sheet of α-iron enriched (∼85%) with57Fe. The electrodeposited Ni and Cr contained oxygen and it could be separated by 500 keV xenon implantation. The separated
oxygen formed an amorphous metal-oxide interphase at the interface of iron substrate and electrodeposited Ni or Cr. 相似文献
47.
Endre Vármonostory 《Order》1992,9(3):239-244
Algebras with an operator that discriminates order are functionally complete. 相似文献
48.
A -hyperfactorization ofK
2n
is a collection of 1-factors ofK
2n
for which each pair of disjoint edges appears in precisely of the 1-factors. We call a -hyperfactorizationtrivial if it contains each 1-factor ofK
2n
with the same multiplicity (then =(2n–5)!!). A -hyperfactorization is calledsimple if each 1-factor ofK
2n
appears at most once. Prior to this paper, the only known non-trivial -hyperfactorizations had one of the following parameters (or were multipliers of such an example)
In the present paper we show the existence of non-trivial simple -hyperfactorizations ofK
2n
for alln5. 相似文献
(i) | 2n=2 a +2, =1 (for alla3); cf. Cameron [3]; |
(ii) | 2n=12, =15 or 2n=24, =495; cf. Jungnickel and Vanstone [8]. |
49.
Gavaghan DJ Gillow K Süli E 《Langmuir : the ACS journal of surfaces and colloids》2006,22(25):10666-10682
In this article, we review some of our previous work that considers the general problem of numerical simulation of the currents at microelectrodes using an adaptive finite element approach. Microelectrodes typically consist of an electrode embedded (or recessed) in an insulating material. For all such electrodes, numerical simulation is made difficult by the presence of a boundary singularity at the electrode edge (where the electrode meets the insulator), manifested by the large increase in the current density at this point, often referred to as the edge effect. Our approach to overcoming this problem has involved the derivation of an a posteriori bound on the error in the numerical approximation for the current that can be used to drive an adaptive mesh-generation algorithm, allowing calculation of the quantity of interest (the current) to within a prescribed tolerance. We illustrate the generic applicability of the approach by considering a broad range of steady-state applications of the technique. 相似文献
50.
M. Samee M. Gadwal Shrikrishina D. Sartale Vikas L. Mathe Habib M. Pathan 《Electrochemistry communications》2009,11(8):1711-1713
The patterned Co layers deposited on the scratched Cu surfaces were investigated with the use of the scanning electron microscopy. Patterned cobalt thin films were electrochemically deposited from the cobalt sulfate bath at room temperature. Pattering of cobalt was carried out by simple means of substrate scratching. Gentle scratching induces a direct pattering of cobalt from vertical to horizontal. The prepared pattered films were characterized for their structural, surface morphological and compositional properties by means of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. X-ray diffraction studies reveal that the films are of cobalt. From the SEM images fabrication of patterns of cobalt is apparent. This work demonstrates a novel approach for obtaining patterned cobalt for many technological applications. 相似文献