Polyhedral Embeddings of Cayley Graphs

When is a Cayley graph the graph of a convex d-polytope? We show that while this is not always the case, some interesting finite groups have this property.     

Dynamic hybrid products with guarantees—An optimal portfolio framework

Dynamic hybrid products are pension products that consist of a dynamic combination of classical with profits participating life insurance contracts (or a bank account) and fund savings plans. To put such products in an optimal utility framework, we derive an optimal combination of a money market account, a CPPI-style fund and a free fund in continuous trading via transforming the original investment problem into a conventional portfolio problem in the presence of a guarantee condition. By this, we obtain (semi-) explicit forms of the dynamic weights for the different ingredients of a dynamic hybrid product.     

Differential Operator Realization of the Exceptional Superalgebra D(2,1;α) and Its Application

In this paper, we give the explicit expressions of the differential operator representations of the exceptional Lie superalgebra D(2,1;α). Based on these expressions, we construct free field realizations of the currents associated with D(2,1;α) at an arbitrary level k.     

Geometric realizations of curvature models by manifolds with constant scalar curvature

We show any pseudo-Riemannian curvature model can be geometrically realized by a manifold with constant scalar curvature. We also show that any pseudo-Hermitian curvature model, para-Hermitian curvature model, hyper-pseudo-Hermitian curvature model, or hyper-para-Hermitian curvature model can be realized by a manifold with constant scalar and -scalar curvature.     

Sum of squares method for sensor network localization

We formulate the sensor network localization problem as finding the global minimizer of a quartic polynomial. Then sum of squares (SOS) relaxations can be applied to solve it. However, the general SOS relaxations are too expensive to implement for large problems. Exploiting the special features of this polynomial, we propose a new structured SOS relaxation, and discuss its various properties. When distances are given exactly, this SOS relaxation often returns true sensor locations. At each step of interior point methods solving this SOS relaxation, the complexity is , where n is the number of sensors. When the distances have small perturbations, we show that the sensor locations given by this SOS relaxation are accurate within a constant factor of the perturbation error under some technical assumptions. The performance of this SOS relaxation is tested on some randomly generated problems.     

Numerical analysis of a water wave model with a nonlocal viscous dispersive term using the diffusive approach

In this paper, we numerically study the water wave model with a nonlocal viscous term where is the Riemann‐Liouville half‐order derivative in time. We propose and compare different numerical schemes based on the diffusive realizations of fractional operators.     

复杂装备研制协调超网络均衡与实现路径

复杂装备研制主体间呈现社会关系、合作关系、协调关系等网络关系,并且相互影响相互作用,其影响复杂装备研制的重要参数。为有效描述在资源环境约束下制造商和供应商的关系,探讨复杂装备研制协调机理与实现路径,本文利用超网络方法,设计了相互影响、相互作用的社会关系网络、协调网络和合作网络的复杂装备研制协调超网络,并将社会关系水平、协调度和合作水平作为超网络的3个决策变量,建立基于关系价值最大、协调成本最低、协调风险最小、合作收益最大、合作风险最小和成本最小等不同偏好下的多目标最优决策模型,构建了复杂装备研制超网络均衡模型,并利用其探讨超网络均衡和实现路径。     

Statistics of isomorphism types in free products

Let Γ be a free product of finitely many finite- and infinite-cyclic groups. For a subgroup Δ of finite index given by its coset representation we compute its isomorphism type, i.e., its decomposition as a free product of finite- and infinite-cyclic groups. We determine the set of isomorphism types realized by finite-index subgroups, the asymptotics of the subgroup numbers with prescribed isomorphism types, and the distribution of the isomorphism types among subgroups of fixed index. Apart from group-theoretic arguments, the proofs of the present paper make use of asymptotic, combinatorial, and probabilistic ideas and techniques.     

高产优质高效农业评价方法和实现途径

本文综述了人们对高产优质高效农业的不同认识，明确提出高产优质高效农业的特征．就评价方法问题，设计了高产优质高效农业的评价指标体系．从实现高产优质高效农业是项系统工程出发，在综合各地经验的基础上，探索了高产优质高效农业的实现途径．