Approximation algorithms for general one‐warehouse multi‐retailer systems

Logistical planning problems are complicated in practice because planners have to deal with the challenges of demand planning and supply replenishment, while taking into account the issues of (i) inventory perishability and storage charges, (ii) management of backlog and/or lost sales, and (iii) cost saving opportunities due to economies of scale in order replenishment and transportation. It is therefore not surprising that many logistical planning problems are computationally difficult, and finding a good solution to these problems necessitates the development of many ad hoc algorithmic procedures to address various features of the planning problems. In this article, we identify simple conditions and structural properties associated with these logistical planning problems in which the warehouse is managed as a cross‐docking facility. Despite the nonlinear cost structures in the problems, we show that a solution that is within ε‐optimality can be obtained by solving a related piece‐wise linear concave cost multi‐commodity network flow problem. An immediate consequence of this result is that certain classes of logistical planning problems can be approximated by a factor of (1 + ε) in polynomial time. This significantly improves upon the results found in literature for these classes of problems. We also show that the piece‐wise linear concave cost network flow problem can be approximated to within a logarithmic factor via a large scale linear programming relaxation. We use polymatroidal constraints to capture the piece‐wise concavity feature of the cost functions. This gives rise to a unified and generic LP‐based approach for a large class of complicated logistical planning problems. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

Beyond Just War: Military Strategy for the Common Good

The objective of this article is to move ethical discourse on military strategy beyond the confines of the established War Convention. This is achieved by utilising the common good, a concept found in political philosophy and theology. The common good acts as a positive organising concept for socio-political activity. With its focus on peace, development and the flourishing of the individual and community, the common good poses a significant challenge to strategy. This article constructs an approach to strategy that is compatible with the common good. Importantly, it does so whilst respecting the pursuit of victory as an indispensable component of strategy’s true nature. The theory presented in this article is then tested in relation to four different modes of strategy: regular war, irregular war, deterrence, and cyberwar.     

Ethnicity,class, and civil war: the role of hierarchy,segmentation, and cross-cutting cleavages

Why are some countries prone to ethno-nationalist conflict, whereas others are plagued by class conflict? This is a question that has seldom been raised and rarely been examined empirically. This paper presents a social-structural theory to account for the variable incidence of these two forms of political instability. These two types of conflict result from distinct principles of group solidarity – ethnicity and class – and since each individual is simultaneously a member of an ethnic group (or many such groups) and a particular class, these two principles vary in the degree to which they are mutually exclusive or cross-cutting. The degree of economic stratification between groups and economic segmentation within them shapes the relative salience of each principle of group solidarity in any society and is associated with a characteristic form of political mobilization. In places where between-group inequalities are high, and within-group inequalities low, ethnicity should be the dominant principle of group solidarity and serve as the primary basis of group conflict. By contrast, in countries where between-group inequalities are low, and within-group inequalities high, class is more likely to serve as the dominant principle of group solidarity, and conflicts along class lines are more likely. We test these conjectures with data in over 100 countries on cross-cutting cleavages, ethnic war, and class conflict. The results are supportive of the theory, and provide evidence that how groups are stratified and segmented in societies shapes the type of civil war.     

Ordering and controlling the dimensions of strategy

Colin Gray’s dimensions of strategy, built upon the earlier work of Clausewitz and Howard, has theoretical, practical, and pedagogic value for the Strategic Studies community. This paper further develops the theory, arguing that the dimensions can be controlled or managed to improve strategic performance. The dimensions are divided into two categories: “internal” and “external” to the process of strategy. The paper describes the dynamic process by which the internal dimensions, which can be controlled, are used to exert influence over the external dimensions that are beyond the control of the strategist. It is argued that six dimensions hold the key to strategic success: politics and the five dimensions concerned with warfighting. This conclusion validates the Clausewitzian paradigm with its emphasis on policy and battle.     

Strength in Numbers: The Labour Government and the Size of the Polaris Force

Previous historical accounts have simplified the Labour government's decision to commission a four-boat strategic nuclear deterrent, or ‘Polaris force’, in early 1965. Utilising previously classified sources, this article shows that a number of key strategic concerns led the decision-making process. Nevertheless, broader economic and diplomatic considerations were also important in determining the size of the Polaris force. A tremendous balance of payments deficit and ongoing debates regarding levels of conventional and nuclear involvement in NATO certainly influenced the government's final decision. Moreover, competing strategic and economic interests resulted in continued debate throughout the decision-making process.     

Communications intelligence and the battle for convoy OG 71, 15–23 August 1941

In 1941, the British instituted a comprehensive system of convoys in the Atlantic. One of the first convoys, OG 71, while sailing between Britain and Gibraltar, was shadowed by German aircraft and attacked by U‐boats. In the ensuing August battle, while no U‐boats were sunk, the British lost, out of a convoy consisting of 22 vessels, two escorts and eight merchant ships. The German victory was not complete owing to the inability of the German aircraft and U‐boats to cooperate successfully as well as the failure of the U‐boats to fight the battle effectively and aggressively. The British also made many mistakes during the defence of Convoy OG 71. The surface escorts made many errors of tactics; as for the British aircraft, owing to an inability to cooperate with the surface forces, they became almost totally ineffective. One bright spot for the British during the battle, however, was communications intelligence. The battle saw the first use of high frequency direction finders and on several occasions skillful use was made of information obtained from enemy radio transmissions. In fact important lessons were learned by the British from such use of communications intelligence which would pave the way for a more effective implementation of such information in future convoy battles.     

Jonathan Boff Winning and Losing on the Western Front. The British Third Army and the Defeat of Germany in 1918.

Building indigenous armies in Asia with military advisory and aid programs has been a mission of the United States Army for over 100 years. Creation of an indigenous army was an early goal of American occupation policy in Korea, but little support and resources were assigned. Between 1946 and 1948, a minute American advisory effort partially trained and equipped a Korean Army cadre of 25,000 men. The unceasing efforts of a talented American advisor, Captain James Hausman, made success possible. He dominated the small advisory group, was given carte blanche to implement his ideas, and left indelible changes on what became the South Korean Army.