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31.
《Mathematische Nachrichten》2017,290(17-18):3029-3037
In this note, we show that any projective subspace arrangement can be realized as a generalized star configuration variety. This type of interpolation result may be useful in designing linear codes with prescribed codewords of minimum weight, as well as in answering a couple of questions about the number of equations needed to define a generalized star configuration variety. 相似文献
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《Discrete Mathematics》2019,342(8):2445-2453
We prove Terao conjecture saying that the freeness is determined by the combinatorics for arrangements of 13 lines in the complex projective plane. 相似文献
35.
Let fs,t(m,n) be the number of (0,1) - matrices of size m x n such that each row has exactly s ones and each column has exactly t ones (sm = nt). How to determine fs,t(m,n)? As R. P. Stanley has observed (Enumerative CombinatoricsⅠ(1997), Example 1.1.3), the determination of fs,t(m, n) is an unsolved problem, except for very small s, t. In this paper the closed formulas for f2,2(n,n), f3,2(m,n), f4,2(m,n) are given. And recursion formulas and generating functions are discussed. 相似文献
36.
In this paper, we propose the construction of merging arrangements for combining the information from various runs as a powerful approach to improve the resolution. The bacteriorhodopsin (bR) photocycle has been chosen in this study as an example dealing with the protein dynamics monitored by means of time-resolved step-scan FT-IR spectroscopy. The possibilities of matrix merging are evaluated and results are compared with those from the analysis of individual and augmented matrices. As a conclusion, this strategy provides excellent results for the analysis of this type of time-resolved FT-IR data. 相似文献
37.
Let A be an n × d matrix having full rank n. An orthogonal dual A⊥ of A is a (d-n) × d matrix of rank (d−n) such that every row of A⊥ is orthogonal (under the usual dot product) to every row of A. We define the orthogonal dual for arrangements by identifying an essential (central) arrangement of d hyperplanes in n-dimensional space with the n × d matrix of coefficients of the homogeneous linear forms for which the hyperplanes are kernels. When n ≥ 5, we show that if the matroid (or the lattice of intersection) of an n-dimensional essential arrangement contains a modular copoint whose complement spans, then the derivation module of the orthogonally dual arrangement
⊥ has projective dimension at least ⌈ n(n+2)/4 ⌉ - 3.Hal Schenck partially supported by NSF DMS 03-11142, NSA MDA 904-03-1-0006, and ATP 010366-0103. 相似文献
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Graham Brightwell 《Discrete Mathematics》2010,310(5):1016-1025
We consider a natural analogue of the graph linear arrangement problem for posets. Let P=(X,?) be a poset that is not an antichain, and let λ:X→[n] be an order-preserving bijection, that is, a linear extension of P. For any relation a?b of P, the distance between a and b in λ is λ(b)−λ(a). The average relational distance of λ, denoted , is the average of these distances over all relations in P. We show that we can find a linear extension of P that maximises in polynomial time. Furthermore, we show that this maximum is at least , and this bound is extremal. 相似文献
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M. A. Omara 《实验传热》2013,26(6):796-810
Natural convection heat transfer characteristics enclosures from a tilted rectangular enclosure heated at the corrugated bottom wall and vented by uniform slots opening at the top wall are experimentally investigated. The experiments were carried out to study the effects of the angle of opening of the corrugated surface, opening ratio, enclosure's tilt angle, and Rayleigh number on the passive cooling of the enclosure. The experiments were carried out at Rayleigh numbers ranging from 2 × 108 to 1.52 × 109 for enclosure tilt angles ranging from 0° to 90° and angle of opening of corrugated surface ranging from 0° to 25°. The top venting arrangement was studied at different opening ratios of 1, 0.75, 0.5, and 0.25. The results gave an optimum angle of opening of the corrugated surface at which Nusselt number is maximum. 相似文献