Polyhedral Combinatorics in Combinatorial Optimization

Polyhedral combinatorics is a subarea of combinatorial optimization of increasing practical importance. It deals with the application of the theory of linear systems and linear algebra to combinatorial problems. The paper is not intended as a survey on polyhedral combinatorics but it reviews some of the main concepts and proof techniques.     

个人所得税功能分析及政策选择

个人所得税是目前增长最快的税种之一 ,是政府用来干预、调节经济活动的重要经济杠杆和调节社会收入分配的重要工具 ,在发挥其作用的同时 ,却产生了对劳动力和私人储蓄的替代效应 ,从我国近几年的运行状况来看 ,个人所得税无论是从税制的最初设计还是征管方面存在着严重不足 ,在政策选择上宜采取综合所得征收制及双向申报制     

An LP-based tabu search for batch scheduling in a cutting process with finite buffers

This paper addresses a cutting stock problem under typical resource constraints that arise when working centres with nesting capabilities are associated with automatic feeders/stackers. The critical resource is the number of buffers available to host the batches built up by the centre. To cope with it, pattern and batch sequencing problems must be addressed simultaneously. A tabu-search algorithm exploring batch output sequences is proposed. The algorithm never opens more stacks than buffers, respects batch compatibility/precedence constraints, and keeps the maximum order spread under control. To demonstrate its effectiveness and efficiency, a computational study was set up, solving 920 test problems derived from the literature. The study enabled a proper tuning of the method and offered encouraging results: in 228 cases an optimum was found; in nearly all, the gap from the optimum was below 1%. Computation times range from fractions of seconds to a couple of minutes in the worst cases. Compared to existing methods, the algorithm provides on average the same solution quality, with the advantage of solving a problem which is more general and hence closer to application. The paper includes a discussion on the method extensions required to deal with asynchronous stacking and heterogeneous batches.     

Assessment of stock size to minimize cutting stock production costs

A method for assessing the optimal stock size for the expected order size for a single-period one-dimensional cutting stock problem is proposed. The stock size is optimal when the expected total costs of trim loss, warehousing, and non-fulfilment are minimum. The stock size is the sum of all bar lengths in the stock, and the order size is the sum of shorter bar lengths in various numbers of pieces. Using simulated test cases, a statistical estimation of optimal stock size is conducted, which in our case is approximately 50% above the expected order. The proposed method can help company choose the appropriate level of stock to minimize their total costs.     

“四阶段法”中运量分配的路网断面剖切技术研究

针对"四阶段法"的运量分配过程中存在对路网动态变化的适应性反应迟钝、相关径路双向交流产生的大量回流量重复计算、通道交流量缺乏总量控制调节关键环节等问题,提出采用路网断面动态剖切技术,给出具体操作步骤和基本算法,并与传统运量分配方法进行优劣分析。通过宝中线运量预测的实例计算分析,说明断面剖切技术的实际应用。     

A novel profit cutting mechanism for Chinese Banks: Theory and Multi-dimensional evidence

As China’s macroeconomic growth faces increasing pressure from the global COVID-19 pandemic, a surprising and politically controversial phenomenon has emerged: the profitability of banks in China exceeded that of enterprises and non-financial industries. The People’s Bank of China and regulatory authorities have hence taken measures to incentivize banks to transfer part of their profits to enterprises, with the aim to stabilize enterprises and employment. This paper proposes a novel profit cutting mechanism focusing on loan structure adjustments to address the limitations of the current approach centering on lowering loan interest rates. The theoretical and empirical analysis show, at both the macro and micro level, that an increase in the proportion of credit loans can benefit the development of enterprises without weakening banks’ operating performance in the long term, leading to a Pareto improvement within enterprise-banking sectors. The findings suggest that banks in China should gradually adjust their loan structures by providing greater credit loan access to enterprises, either voluntarily or directed by policy.     

北方寒地中华金叶榆扦插育苗快速繁殖技术研究

中华金叶榆是目前我国北方高寒地区景观园林中使用量最大的一种彩叶树。现主要存在苗木繁殖速度慢,育苗成本高,苗木质量不高等问题。本文综述了北方寒地扦插育苗快速繁殖中华金叶榆的简易技术和方法,为高寒地区繁殖和生产中华金叶榆苗木提供技术指导和参考。     

Loading optimization of palletized products on trucks

In this paper we analyze the application of an optimization model to solve problems of arranging products (packed in boxes) on pallets, and arranging loaded pallets on trucks. Initially the model is applied to solve thousands of randomly generated experiments. Then, in order to assess the effectiveness of the solutions in practice, the model is applied to two Brazilian case studies: a food company distribution center and a large wholesale distribution center. We also discuss the use of this approach for optimizing the sizes of packages, pallets and trucks. In particular, we analyze the performance of the Brazilian standard pallet (PBR), adopted by the Brazilian Association of Supermarkets (ABRAS) and recommended by the Brazilian Logistics Association (ASLOG), in comparison with other standard pallets. By examining not only the loading of products on pallets, but also the loading of pallets on trucks, we can obtain global utilization indices which are useful to evaluate the economical performance of unit load systems in the logistics chain of a company.     

Automatic Editing for Business Surveys: An Assessment of Selected Algorithms

Statistical offices are responsible for publishing accurate statistical information about many different aspects of society. This task is complicated considerably by the fact that data collected by statistical offices generally contain errors. These errors have to be corrected before reliable statistical information can be published. This correction process is referred to as statistical data editing. Traditionally, data editing was mainly an interactive activity with the aim to correct all data in every detail. For that reason the data editing process was both expensive and time-consuming. To improve the efficiency of the editing process it can be partly automated. One often divides the statistical data editing process into the error localisation step and the imputation step. In this article we restrict ourselves to discussing the former step, and provide an assessment, based on personal experience, of several selected algorithms for automatically solving the error localisation problem for numerical (continuous) data. Our article can be seen as an extension of the overview article by Liepins, Garfinkel & Kunnathur (1982). All algorithms we discuss are based on the (generalised) Fellegi–Holt paradigm that says that the data of a record should be made to satisfy all edits by changing the fewest possible (weighted) number of fields. The error localisation problem may have several optimal solutions for a record. In contrast to what is common in the literature, most of the algorithms we describe aim to find all optimal solutions rather than just one. As numerical data mostly occur in business surveys, the described algorithms are mainly suitable for business surveys and less so for social surveys. For four algorithms we compare the computing times on six realistic data sets as well as their complexity.     

Seguridad social y rendimiento empresarial. El caso de las pymes vietnamitas

Se investiga cómo la provisión de cobertura social –un factor clave de la formalidad– afecta al rendimiento de las pymes en Viet Nam. Con datos censales de todas las empresas declaradas de 2006 a 2011, los autores encuentran que las que aumentan su cobertura social en un 10 por ciento experimentan un aumento del ingreso por trabajador del 1,4 al 2 por ciento y un incremento del beneficio de hasta el 1,8 por ciento, dependiendo del tiempo de supervivencia. Sin embargo, dado el desfase entre la «inversión» y sus retornos (mejora del rendimiento), medidas como la subvención de las cotizaciones iniciales podrían incentivar la participación en los regímenes obligatorios.