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91.
The Team Orienteering Problem (TOP) is the generalization to the case of multiple tours of the Orienteering Problem, known
also as Selective Traveling Salesman Problem. A set of potential customers is available and a profit is collected from the
visit to each customer. A fleet of vehicles is available to visit the customers, within a given time limit. The profit of
a customer can be collected by one vehicle at most. The objective is to identify the customers which maximize the total collected
profit while satisfying the given time limit for each vehicle. We propose two variants of a generalized tabu search algorithm
and a variable neighborhood search algorithm for the solution of the TOP and show that each of these algorithms beats the
already known heuristics. Computational experiments are made on standard instances. 相似文献
92.
An analog of the minimal unitary series representations for the deformed Virasoro algebra is constructed using vertex operators of the quantum affine algebra Uq(sl2). A similar construction is proposed for the elliptic algebra Aq,p(sl2). 相似文献
93.
94.
Don Zagier 《Proceedings Mathematical Sciences》1994,104(1):57-75
In 1956, Rankin described which polynomials in the derivatives of modular forms are again modular forms, and in 1977, H Cohen
defined for eachn ≥ 0 a bilinear operation which assigns to two modular formsf andg of weightk andl a modular form [f, g]n of weightk +l + 2n. In the present paper we study these “Rankin-Cohen brackets” from two points of view. On the one hand we give various explanations
of their modularity and various algebraic relations among them by relating the modular form theory to the theories of theta
series, of Jacobi forms, and of pseudodifferential operators. In a different direction, we study the abstract algebraic structure
(“RC algebra”) consisting of a graded vector space together with a collection of bilinear operations [,]n of degree + 2n satisfying all of the axioms of the Rankin-Cohen brackets. Under certain hypotheses, these turn out to be
equivalent to commutative graded algebras together with a derivationS of degree 2 and an element Φ of degree 4, up to the equivalence relation (∂,Φ) ~ (∂ - ϕE, Φ - ϕ2 + ∂(ϕ)) where ϕ is an element of degree 2 andE is the Fuler operator (= multiplication by the degree).
Dedicated to the memory of Professor K G Ramanathan 相似文献
95.
96.
In a recent paper [O. Bärwald, R.W. Gebert, M. Günaydin and H. Nicolai, preprint KCL-MTH-97-22, IASSNS-HEP-97/20, PSU-TH-178, AEI-029, hep-th/9703084, to appear in Commun. Math. Phys.] it was conjectured that the imaginary simple roots of the Borcherds algebra II9,1 at level 1 are its only ones. We here propose an independent test of this conjecture, establishing its validity for all roots of norm − 8. However, the conjecture fails for roots of norm −10 and beyond, as we show by computing the simple multiplicities down to norm −24, which turn out to be remarkably small in comparison with the corresponding E10 multiplicities. Our derivation is based on a modified denominator formula combining the denominator formulas for E10 and II9,1, and provides an efficient method for determining the imaginary simple roots. In addition, we compute the E10 multiplicities of all roots up to height 231, including levels up to l = 6 and norms −42. 相似文献
97.
It is proved that in many cases of interest the actions of groups on rooted trees can be recovered from the structure of the groups. The results apply to most of the groups introduced by the first author and to the Gupta–Sidki groups; they are proved in the wider context of branch groups satisfying two natural conditions. 相似文献
98.
A unifying zero-zone function concept extends the Lagrange method of undetermined multipliers to treat both equality and inequality subsidiary conditions. The mathematical formulation is general for restrained function extremization in algebra. 相似文献
99.
基于高斯混合尺度模型的压缩传感图像重构 总被引:1,自引:0,他引:1
在图像处理领域中,压缩传感重构是稀疏表示下的最重要的病态反问题之一。压缩传感图像重构利用图像可稀疏表示的先验知识,从比奈奎斯特采样率低得多的随机投影观测值中重构原始图像。为了克服传统的压缩传感算法中收敛速度慢和未利用变换系数的邻域统计特性的缺点,提出了基于高斯混合尺度模型的压缩传感图像重构算法,证明了独立的高斯混合尺度分布作为压缩传感重构的稀疏先验知识的可行性,结合全变差调整进一步提高算法的性能。实验结果表明,该算法有效地提高了重构图像的主观视觉效果和峰值信噪比,加快了压缩传感图像重构算法的收敛速度。 相似文献
100.
By using the rigorous spectral representation of relativistic random phase approximation, the low-lying excitation of finite nuclei and its longitudinal response function for quasielastic electron scattering are calculated in the σ-ω model of quantum hadrodynamics. It is shown that the reproduction of the correct order of the 1- and 3- excitation states of 16O is due to the contribution of the exchange vertex. There is no significant influence of the retardation effect on the low-lying excitation states. In contrast, the retardation effect plays an important role in the electron scattering process of nuclei. The theoretical longitudinal responses of 12C and 40Ca, including the contributions of the exchange vertex and the retardation effect, are suppressed and reproduce the experimental data better than the results excluding them. 相似文献