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991.
对树的3-彩虹控制数进行研究,首先用构造法找到直径较小的树的3-彩虹控制数的上界.再通过分类讨论思想和数学归纳法得到一般的阶n大于等于5的树的3-彩虹控制数的上界. 相似文献
992.
993.
Handan Borluk Gulcin M. Muslu 《Numerical Methods for Partial Differential Equations》2015,31(4):995-1008
In this article, we propose a Fourier pseudospectral method for solving the generalized improved Boussinesq equation. We prove the convergence of the semi‐discrete scheme in the energy space. For various power nonlinearities, we consider three test problems concerning the propagation of a single solitary wave, the interaction of two solitary waves and a solution that blows up in finite time. We compare our numerical results with those given in the literature in terms of numerical accuracy. The numerical comparisons show that the Fourier pseudospectral method provides highly accurate results. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 995–1008, 2015 相似文献
994.
Let C be a given circuit of a bridgeless cubic graph G. It was conjectured by Seymour that G has a circuit double cover (CDC) containing the given circuit C. This conjecture (strong CDC [SCDC] conjecture) has been verified by Fleischner and Häggkvist for various families of graphs and circuits. In this article, some of these earlier results have been improved: (1) if contains a Hamilton path or a Y‐tree of order less than 14, then G has a CDC containing C; (2) if is connected and , then G has a CDC containing C. 相似文献
995.
996.
Considering the most general one-species reaction-diffusion processes on a Cayley tree, it has been shown that there exist two integrable models. In the first model, the reactions are the various creation processes, i.e. °°→•°, °°→•• and °•→••, and in the second model, only the diffusion process •°→°• exists. For the first model, the probabilities Pl(m;t), of finding m particles on the lth shell of the Cayley tree, have been found exactly, and for the second model, the functions Pl(1;t) have been calculated. It has been shown that these are the only integrable models if one restricts consideration to the L+1-shell probabilities P(m0,m1,…,mL;t). 相似文献
997.
Alina Serb Catalin Schiopu Corina Flangea Eugen Sisu Alina D. Zamfir 《Journal of mass spectrometry : JMS》2009,44(10):1434-1442
We developed a straightforward approach for high‐throughput top–down glycolipidomics based on fully automated chip‐nanoelectrospray (nanoESI) high‐capacity ion trap (HCT) multistage mass spectrometry (MSn) by collision‐induced dissociation (CID) in the negative ion mode. The method was optimized and tested on a polysialylated ganglioside fraction (GT1b), which was profiled by MS1 and sequenced in tandem MS up to MS6 in the same experiment. Screening of the fraction in the MS1 mode indicated the occurrence of six [M ? 2H]2? ions which, according to calculation, support 13 GT1 variants differing in their relative molecular mass due to dissimilar ceramide (Cer) constitutions. By stepwise CID MS2–MS5 on the doubly charged ion at m/z 1077.20 corresponding to a ubiquitous GT1b structure, the complete characterization of its oligosaccharide core including the identification of sialylation sites was achieved. Structure of the lipid moiety was further elucidated by CID MS6 analysis carried out using the Y0 fragment ion, detected in MS5, as a precursor. MS6 fragmentation resulted in a pattern supporting a single ceramide form having the less common (d20 : 1/18 : 0) configuration. The entire top–down experiment was performed in a high‐throughput regime in less than 3 min of measurement, with an analysis sensitivity situated in the subpicomolar range. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
998.
Let G be a connected graph and T be a spanning tree of G. For e∈E(T), the congestion of e is the number of edges in G connecting two components of T−e. The edge congestion ofGinT is the maximum congestion over all edges in T. The spanning tree congestion ofG is the minimum congestion of G in its spanning trees. In this paper, we show the spanning tree congestion for the complete k-partite graphs and the two-dimensional tori. We also address lower bounds of spanning tree congestion for the multi-dimensional grids and the hypercubes. 相似文献
999.
Srikrishnan Divakaran 《Discrete Applied Mathematics》2009,157(7):1407-1422
In generalized tree alignment problem, we are given a set S of k biologically related sequences and we are interested in a minimum cost evolutionary tree for S. In many instances of this problem partial phylogenetic tree for S is known. In such instances, we would like to make use of this knowledge to restrict the tree topologies that we consider and construct a biologically relevant minimum cost evolutionary tree. So, we propose the following natural generalization of the generalized tree alignment problem, a problem known to be MAX-SNP Hard, stated as follows:
Constrained Generalized Tree Alignment Problem [S. Divakaran, Algorithms and heuristics for constrained generalized alignment problem, DIMACS Technical Report 2007-21, 2007]: Given a set S of k related sequences and a phylogenetic forest comprising of node-disjoint phylogenetic trees that specify the topological constraints that an evolutionary tree of S needs to satisfy, construct a minimum cost evolutionary tree for S.In this paper, we present constant approximation algorithms for the constrained generalized tree alignment problem. For the generalized tree alignment problem, a special case of this problem, our algorithms provide a guaranteed error bound of 2−2/k. 相似文献
1000.
In this paper a method is given to calculate the explicit expressions of embedding genus distribution for ladder type graphs
and cross type graphs. As an example, we refind the genus distribution of the graph J
n
which is the first class of graphs studied for genus distribution where its genus depends on n.
This work was supported National Natural Science Foundation of China (Grant Nos. 10571013, 60433050) and the State Key Development
Program of Basic Research of China (Grant No. 2004CB318004) 相似文献