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排序方式: 共有566条查询结果,搜索用时 15 毫秒
541.
We prove the ampleness of the cotangent bundle of the intersection of two general translates of a theta divosor of the Jacobian of a general curve of genus . From this, we deduce the same result in a general, principally polarized abelian variety of dimension .
542.
LetM
1 andM
2 be matroids onS,B be theirk-element common independent set, andw a weight function onS. Given two functionsb 0 andc 0 onS, the Inverse Matroid Intersection Problem (IMIP) is to determine a modified weight functionw such that (a)B becomes a maximum weight common independent set of cardinalityk underw, (b)c¦w — w¦ is minimum, and (c)¦w — w b. Many Inverse Combinatorial Optimization Problems can be considered as the special cases of the IMIP.In this paper we show that the IMIP can be solved in strongly polynomial time, and give a necessary and sufficient condition for the feasibility of the IMIP. Finally we extend the discussion to the version of the IMIP with Multiple Common Independent Sets.Research partially supported by the National Natural Science Foundation of China 相似文献
543.
In this paper we derive some general conditions on stable walks inZ
d
, under which the central limit theorem holds for their normalized intersection local time. In particular, we prove that the process given by the normalized intersection local time of the simple random walk inZ
d
, withd3, is weakly convergent to the standard Brownian motion.BiBoS; SFB 237 Bochum-Essen-Düsseldorf; CERFIM, Locarno. 相似文献
544.
Hong-meiWu Gao-yuanWei 《高分子科学》2004,(4):355-362
Three new kinds of molecular networks are designed and predicted to exhibit negative Poisson ratios. Molecular mechanics calculations on these networks show that the magnitude of Poisson ratios depends on the relative flexibility of beam and arm structures. Several new kinds of auxetic polymers, whose successful synthesis should be easier than that of the corresponding auxetic networks, are then proposed. It is found that the kabob-like polymers with auxegens lying vertically on the main chain can acquire auxeticity while those with auxegens lying horizontally on the main chain cannot. Besides, a half kabob-like or pseudo-ladder polymer with auxegens linked at the intersection of the beam and the arm does show auxeticity when adopting constrictive conformers. It is, however, worthwhile noting that the origins of auxeticity still await and strongly deserve further experimental and theoretical investigations. 相似文献
545.
Quenching of Li (2P) by H2: potential energy surfaces, conical intersection seam, and diabatic bases
The quenching of Li (1s
22p; 2P) to Li (1s
22s; 2S) by H2 is considered using coupled-cluster and multireference configuration-interaction techniques. C
2
v
(2A1, 2B2) and C
∞
v
(2Π,2Σ+) sections of the 12A′ and 22A′ potential energy surfaces are determined. The C
2
v
portion of the 12A′−22A′ seam of conical intersection is studied. Perhaps the most significant finding is a surprising trifurcation of this seam into
a portion with only C
s
symmetry and the aforementioned C
2
v
portion. The adiabatic-to-diabatic state transformation is considered in the vicinity of the seam of conical intersection
using both perturbation theory and the dipole moment operator. The 2B2 section of the 22A′ potential energy surface exhibits an exciplex in the general vicinity of the seam of conical intersection. The 2Π section of the 22A′ potential energy surface possesses a global minimum lying 1.86kcal/mol below the Li (2P)+H2 asymptote. A van der Waals-like minimum with C
∞
v
symmetry was found on the 12A′ potential energy surface.
Received: 14 August 1998 / Accepted: 20 August 1998 / Published online: 11 November 1998 相似文献
546.
547.
In this paper, we present a conjecture that is a common generalization of the Doyen–Wilson Theorem and Lindner and Rosa's intersection theorem for Steiner triple systems. Given u, v ≡ 1,3 (mod 6), u < v < 2u + 1, we ask for the minimum r such that there exists a Steiner triple system such that some partial system can be completed to an STS , where |?| = r. In other words, in order to “quasi‐embed” an STS(u) into an STS(v), we must remove r blocks from the small system, and this r is the least such with this property. One can also view the quantity (u(u ? 1)/6) ? r as the maximum intersection of an STS(u) and an STS(v) with u < v. We conjecture that the necessary minimum r = (v ? u) (2u + 1 ? v)/6 can be achieved, except when u = 6t + 1 and v = 6t + 3, in which case it is r = 3t for t ≠ 2, or r = 7 when t = 2. Using small examples and recursion, we solve the cases v ? u = 2 and 4, asymptotically solve the cases v ? u = 6, 8, and 10, and further show for given v ? u > 2 that an asymptotic solution exists if solutions exist for a run of consecutive values of u (whose required length is no more than v ? u). Some results are obtained for v close to 2u + 1 as well. The cases where ≈ 3u/2 seem to be the hardest. © 2004 Wiley Periodicals, Inc. 相似文献
548.
Regina Sandra Burachik Vaithilingam Jeyakumar 《Proceedings of the American Mathematical Society》2005,133(6):1741-1748
In this paper it is shown that if and are two closed convex subsets of a Banach space and , then whenever the convex cone, , is weak* closed, where and are the support function and the normal cone of the set respectively. This closure condition is shown to be weaker than the standard interior-point-like conditions and the bounded linear regularity condition.
549.
E. Muñoz Garcia 《Compositio Mathematica》2000,124(3):219-252
Let f:XSbe a projective morphism of Noetherian schemes. We assume fpurely of relative dimension dand finite Tor-dimensional. We associate to d+1 invertible sheaves
on Xa line bundle I
X/S
(
) on Sdepending additively on the
, commuting to good base changes and which represents the integral along the fibres of fof the product of the first Chern classes of the
. If d=0, I
X/S
(
) is the norm N
X/S
(
). 相似文献
550.
Ahmed Abbes 《Compositio Mathematica》2000,122(1):23-111
We develop a localized intersection theory for arithmetic schemes on the model of Fulton's intersection theory. We prove a Lefschetz fixed point formula for arithmetic surfaces, and give an application to a conjecture of Serre on the existence of Artin's representations for regular local rings of dimension 2 and unequal characteristic. 相似文献