Paul Wentges

Weighted Dantzig-Wolfe decomposition for linear mixed-integer programming

Dantzig-Wolfe decomposition can be used to solve the Lagrangian dual of a linear mixed-integer programming problem (MIP) if the dual structure of the (MIP) is exploited via Lagrangian relaxation with respect to the complicating constraints. In the so-called weighted Dantzig-Wolfe decomposition algorithm, instead of the optimal solution of the Dantzig-Wolfe master problem a specially weighted average of the previously constructed Lagrangian multipliers and the optimal solution of the master problem is used as Lagrangian multiplier for the next Lagrangian subproblem to be solved. A convergence proof of the weighted Dantzig-Wolfe decomposition algorithm is given, and some properties of this procedure together with computational results for the capacitated facility location problem are discussed.

Editorial for Special Edition: The convergence concept in cross-cultural management research

management research is the so-called convergence–divergence debate. Representatives of the convergence approach (e.g. Kerr et al., 1960; Eisenstadt, 1973; Levitt, 1983; Prentice, 1990; Waters, 1995; Tomlinson, 1999) perceive management as largely independent from the respective national culture, and focus instead on the importance of learning from best practice in order to increase national competitiveness. They argue that the international competitive pressure will ultimately lead to a convergence of management practices toward those ‘best practices’. On the other side of the debate, adherents of the so-called divergence approach emphasize that management practices are strongly influenced by the relevant national cultural and institutional context (e.g. Laurent, 1983; Hickson and Pugh, 2001; Whitley, 2000; Hofstede, 2001). Consequently, these authors are much more sceptical about the possibility of adopting management practices that evolved outside the respective cultural or institutional context and see little room for cross-national convergence of management processes. This debate is significantly influenced by the advent of the multi-faceted phenomenon termed ‘globalization’. It is often stated that globalization leads to more convergence and standardization in areas such as the management of companies, economic policies, politics and even, culturally, in terms of how we lead our lives. Common examples include the increasing importance of shareholder value, the narrowing of national interest rates, the spread of democracy, the convergence of consumer tastes and the worldwide appeal of some global brands. Sceptics, however, argue that even though management practices may converge at a strategic level, we will see less change in terms of how people really behave. Special Section

On Cross Decomposition for Mixed-Integer Programming

Primal and dual decomposition procedures can lead – dependent on the structure of the problem – to efficient procedures for solving mixed—integer programming problems. Benders’ decomposition takes advantage of the primal structure of a problem by temporarily fixing the aggravating integer variables, while dual structures can be exploited by relaxing the complicating constraints in Lagrangian fashion and solving the Lagrangian dual with subgradient optimization, multiplier adjustment methods, or Dantzig-Wolfe decomposition.

On Bayesian group sequential sampling procedures

A general group sequential statistical decision model is investigated. Using a Bayesian approach and Bayesian dynamic programming, we examine structural properties of the cost functions and of optimal sampling procedures. In particular, we consider variable-sample-size-sequential probability ratio tests and show that the so-called onion-skins conjecture is false.

Theorie der Unternehmung

In der Einleitung wurde bereits darauf hingewiesen, das die Analyse der Corporate Governance-Problematik und auch finanzwirtschaftlicher Fragestellungen immer auf Basis einer bestimmten unternehmenstheoretischen Konzeption bzw. zumindest einer vagen Vorstellung vom Wesen einer Unternehmung vorgenommen wird. Sowohl der Stakeholder-Ansatz als auch das Shareholder Value-Konzept entspringen speziellen Unternehmenssichtweisen. Ziel dieses einleitenden Kapitels ist es daher, die wesentlichen Stromungen der Theorie der Unternehmung darzustellen und vor allem die Wurzeln dieser beider Ansatze herauszuarbeiten.

A Stakeholder Approach to the Valuation of Corporate Cash Flows

Since real-world capital markets are not complete and perfect, the value of cash flow streams cannot be derived from market prices alone. Although different shareholders may prefer different investment strategies, however, they agree that corporate cash flows must not be dominated by alternative cash flows available in the market. Hence, capital markets determine a margin for valuation and the question arises, which principles of corporate planning are adequate for selecting a particular valuation within this margin. We argue that the preservation of the present value of generated cash flows over time (i.e. restricting paid out dividends to the created income) is a well-reasoned principle which is, moreover, well-established in most European corporate governance systems. The paper focuses on the implementation of this principle into standard models for corporate financial planning.