Weighted Perfect Matching with Constraints on the Total Weight of Its Parts

Journal of Applied and Industrial Mathematics - Under consideration is the following strongly NP-hard problem: Given a balanced complete bipartite graph with weights on the edges and a partition of...     

求最优权对集的一个对偶算法

1.引言 Edmonds给出了求一个图的最大权对集的算法它是从一个满足原始对偶可行的解出发使其逐步满足互补松驰条件。[1]描述了一个求最大权完美对集原始算法。它是从一个满足互补松驰条件的原始可行解出发,使其逐步满足对偶可行条件。我们给出一个求图的最大权完美对集的对偶算法,它是从一个满足互补松驰条件的对偶可行解出发使其逐步满足可行条件。本算法开始不要求给出图的一个完全对集,其对偶变量的改变法则也较[1]中的法则简单得多。其基本方法仍是用Edmonds的花的算法[2]。我们将说明本文的算法可用来解其他的最优对集问题。本文中采用的术语参看[2]。     

扩展双系统估计模型及其匹配性质研究

双系统估计模型以往在美国人口普查涵盖测量调查中主要用来测量净误差,美国2010年人口普查涵益测量中考虑依据Mulry和Kostanich提出的误差框架测量普查涵盖误差的构成。本文分析了双系统估计模型理论与其在人口普查实践应用中的不足,通过增加两项模型基本假设,结合前人研究,提出构建适用于一般普查类型的扩展双系统估计模型,通过证明其两条重要的匹配性质,验证了有关学者的研究假设;以此为基础,结合现有数据条件,讨论了基于双系统估计模型原理的普查涵盖误差测量应用.     

图在三种约束条件下的正常全染色

设f:V(G)∪E(G)→{1,2,…,k}是简单图G的一个正常k-全染色.令C(f,u)={f(e):e∈N_e(u)},C[f,u]=C(f,u)∪{f(u)},C_2[f,u]=C(f,u)∪{f(x):x∈N(u)}∪{f(u)}.N(u)表示顶点u的邻集,N_e(u)表示与顶点u的相关联的边的集合.令C[f;x]={C(f,x);C[f,x];C_2[f,x]},对任意的xy∈E(G),G[f;x]≠C[f;y]表示C(f,x)≠C(f,y),C[f,x]≠C[f,y],C_2[f,x]≠C_3[f,y]同时成立.对任意的边xy∈E(G),如果有C[f;x]≠C[f;y]成立,则称f是图G的一个k-(3)-邻点可区别全染色(简记为(3)-AVDTC).图G的(3)-邻点可区别全染色中最小的颜色数叫做G的(3)-邻点可区别全色数,记为x_((3)as)″(G).研究了联图,完全二部图的(3)-邻点可区别全染色,得到了它们的(3)-邻点可区别全色数.     

Matching Properties in Total Domination Vertex Critical Graphs

A vertex subset S of a graph G = (V,E) is a total dominating set if every vertex of G is adjacent to some vertex in S. The total domination number of G, denoted by γ _t (G), is the minimum cardinality of a total dominating set of G. A graph G with no isolated vertex is said to be total domination vertex critical if for any vertex v of G that is not adjacent to a vertex of degree one, γ _t (G?v) < γ _t (G). A total domination vertex critical graph G is called k-γ _t -critical if γ _t (G) = k. In this paper we first show that every 3-γ _t -critical graph G of even order has a perfect matching if it is K _1,5-free. Secondly, we show that every 3-γ _t -critical graph G of odd order is factor-critical if it is K _1,5-free. Finally, we show that G has a perfect matching if G is a K _1,4-free 4-γ _t (G)-critical graph of even order and G is factor-critical if G is a K _1,4-free 4-γ _t (G)-critical graph of odd order.     

有根森林优先约束的单机随机排序问题

讨论单机随机排序问题,目标函数为确定工件的排列顺序使工件的加权完工时间和的数学期望最小.设工件间的优先约束为有根森林,机器发生随机故障.对此情况,给出了多项式时间的最优算法.     

Imposing Minimax and Quantile Constraints on Optimal Matching in Observational Studies

Modern methods construct a matched sample by minimizing the total cost of a flow in a network, finding a pairing of treated and control individuals that minimizes the sum of within-pair covariate distances subject to constraints that ensure distributions of covariates are balanced. In aggregate, these methods work well; however, they can exhibit a lack of interest in a small number of pairs with large covariate distances. Here, a new method is proposed for imposing a minimax constraint on a minimum total distance matching. Such a match minimizes the total within-pair distance subject to various constraints including the constraint that the maximum pair difference is as small as possible. In an example with 1391 matched pairs, this constraint eliminates dozens of pairs with moderately large differences in age, but otherwise exhibits the same excellent covariate balance found without this additional constraint. A minimax constraint eliminates edges in the network, and can improve the worst-case time bound for the performance of the minimum cost flow algorithm, that is, a better match from a practical perspective may take less time to construct. The technique adapts ideas for a different problem, the bottleneck assignment problem, whose sole objective is to minimize the maximum within-pair difference; however, here, that objective becomes a constraint on the minimum cost flow problem. The method generalizes. Rather than constrain the maximum distance, it can constrain an order statistic. Alternatively, the method can minimize the maximum difference in propensity scores, and subject to doing that, minimize the maximum robust Mahalanobis distance. An example from labor economics is used to illustrate. Supplementary materials for this article are available online.     

基于服务距离限制和匹配运输的工厂选址问题

研究供应链背景下一种新的工厂选址问题。在考虑一般选址因素的基础之上,着重讨论不同的服务距离限制对工厂选址、工厂车辆分配过程以及运输网络产生的影响。本文中服务距离限制是指对顾客和供应商进行匹配运输的车辆具有的最大配送距离,运输网络采用顾客和供应商匹配方式。根据上述特点构建了一个多阶段线性整数规划模型。采用cp lex软件对模型进行优化求解。最后通过算例说明所建模型的实用性。     

Dual Bounds and Optimality Cuts for All-Quadratic Programs with Convex Constraints

A central problem of branch-and-bound methods for global optimization is that often a lower bound do not match with the optimal value of the corresponding subproblem even if the diameter of the partition set shrinks to zero. This can lead to a large number of subdivisions preventing the method from terminating in reasonable time. For the all-quadratic optimization problem with convex constraints we present optimality cuts which cut off a given local minimizer from the feasible set. We propose a branch-and-bound algorithm using optimality cuts which is finite if all global minimizers fulfill a certain second order optimality condition. The optimality cuts are based on the formulation of a dual problem where additional redundant constraints are added. This technique is also used for constructing tight lower bounds. Moreover we present for the box-constrained and the standard quadratic programming problem dual bounds which have under certain conditions a zero duality gap.     

Dual Representation of the Cost of Designing a Portfolio Satisfying Multiple Risk Constraints

ABSTRACT

We consider, within a Markovian complete financial market, the problem of finding the least expensive portfolio process meeting, at each payment date, three different types of risk criterion. Two of them encompass an expected utility-based measure and a quantile hedging constraint imposed at inception on all the future payment dates, while the other one is a quantile hedging constraint set at each payment date over the next one. The quantile risk measures are defined with respect to a stochastic benchmark and the expected utility-based constraint is applied to random payment dates. We explicit the Legendre-Fenchel transform of the pricing function. We also provide, for each quantile hedging problem, a backward dual algorithm allowing to compute their associated value function by backward recursion. The algorithms are illustrated with a numerical example.     

A Dual Algorithm for Minimizing a Quadratic Function with Two Quadratic Constraints

In this paper, we present a dual algorithm for minimizing a convex quadratic function with two quadratic constraints. Such a minimization problem is a subproblem that appears in some trust region algorithms for general nonlinear programming. Some theoretical properties of the dual problem are given. Global convergence of the algorithm is proved and a local superlinear convergence result is presented. Numerical examples are also provided.     

Integrality properties of edge path tree families

An Edge Path Tree (EPT) family is a family whose members are edge sets of paths in a tree. Relying on the notion of Pie introduced in [M.C. Golumbic, R.E. Jamison, The edge intersection graphs of paths in a tree, Journal of Combinatorial Theory, Series B 38 (1985) 8-22], we characterize Ideal and Mengerian EPT families. In particular, we show that an EPT family is Ideal if and only if it is Mengerian. If, in addition, the EPT family is uniform, then it is Ideal if and only if it is Unimodular. The latter equivalence generalizes the well-known fact that the edge set of a graph is an Ideal clutter if and only if the graph is bipartite.     

资源受限下森林火灾应急救援多目标调度优化

许多森林火灾由于救援资源受限而不能在第一时间扑灭,导致火灾扩大蔓延,进而造成更大的森林资源损失。因此,在救援资源受限情形下,如何对消防救援车辆进行合理的调度安排以快速和低成本地扑灭火灾已成为亟待解决的现实问题。本文研究了一类资源受限下森林火灾应急救援多目标调度优化问题,为该问题构建了多目标混合整数非线性规划模型,优化目标为同时最小化总灭火救援时间和救援车辆总行驶距离。为有效求解该问题,首先将上述非线性模型等价转化为线性模型。然后提出ε-约束法和模糊逻辑相结合的算法对问题进行求解。最后,以大兴安岭山发生的火灾案例和随机生成仿真算例对模型和算法有效性进行验证,结果表明所提出的模型和算法能够有效解决资源受限下森林火灾应急救援问题,并为决策者提供最优的消防调度方案。     

Preemptive Scheduling with Availability Constraints to Minimize Total Weighted Completion Times

In this paper we study the problem of scheduling n jobs on a single machine with availability constraints. The objective is to minimize total weighted job completion times. We show that the problem is NP-hard in the strong sense. Then we consider two intractable special cases, namely, proportional weight case, and single availability constraint case. We propose two heuristics for these cases and analyze their worst-case error bounds.     

Integrality and gauge dependence of Hennings TQFTs

We provide a general construction of integral TQFTs over a general commutative ring, $\mathbb{k}$, starting from a finite Hopf algebra over $\mathbb{k}$ which is Frobenius and double balanced. These TQFTs specialize to the Hennings invariants of the respective doubles on closed 3-manifolds.We show the construction applies to index 2 extensions of the Borel parts of Lusztig's small quantum groups for all simple Lie types, yielding integral TQFTs over the cyclotomic integers for surfaces with one boundary component.We further establish and compute isomorphisms of TQFT functors constructed from Hopf algebras that are related by a strict gauge transformation in the sense of Drinfeld. Formulas for the natural isomorphisms are given in terms of the gauge twist element.These results are combined and applied to show that the Hennings invariant associated to quantum-${\mathfrak{sl}}_2$ takes values in the cyclotomic integers. Using prior results of Chen et al. we infer integrality also of the Witten–Reshetikhin–Turaev $SO(3)$ invariant for rational homology spheres.As opposed to most other approaches the methods described in this article do not invoke calculations of skeins, knots polynomials, or representation theory, but follow a combinatorial construction that uses only the elements and operations of the underlying Hopf algebras.     

Partitioning a Planar Graph of Girth 10 into a Forest and a Matching

We prove that any finite planar graph with girth at least 10 can have its edges partitioned to form two graphs on the same vertices, one of which is a forest, and the other of which is a matching. Several related results are also demonstrated.     

Integrality of Power Expansions Related to Hypergeometric Series

In the present paper, we study the arithmetic properties of power expansions related to generalized hypergeometric differential equations and series. Defining the series f(z),g(z) in powers of z so that f(z) and satisfy a hypergeometric equation under a special choice of parameters, we prove that the series in powers of z and its inversion z(q) in powers of q have integer coefficients (here the constant C depends on the parameters of the hypergeometric equation). The existence of an integral expansion z(q) for differential equations of second and third order is a classical result; for orders higher than 3 some partial results were recently established by Lian and Yau. In our proof we generalize the scheme of their arguments by using Dwork's p-adic technique.     

Integrality of the symmetric algebra of graph ideals

We consider edge ideals associated to some classes of simple graphs and study the projective dimension and the integrality of the symmetric algebra for them. We also analyze criteria for torsion freeness of the symmetric powers and determine conditions of acyclicity of the Z-complex of these graph ideals.