The Markowitz mean-variance portfolio optimization problem is a quadratic programming problem whose first-order conditions require the solution of a linear system. It is well known that the optimal portfolio weights are sensitive to parameter estimates, particularly the mean return vector. This...

In this paper we consider the problem of locating an axis-parallel rectangle in the plane such that the sum of distances between the rectangle and a finite point set is minimized, where the distance is measured by the Manhattan norm ℓ <Subscript>1</Subscript>. In this way we solve an extension of the Weber problem...</subscript>

Measurements for fitting a given number of concentric circles are recorded. For each concentric circle several measurements are taken. The problem is to fit the given number of circles to the data such that all circles have a common center. This is a generalization of the problem of fitting a...

This paper presents a general mixed-norm minisum problem for locating a single facility in continuous space. It is assumed that several transportation modes exist between the new facility and a given set of fixed points (the customers), each mode being represented by a different ℓ <Subscript> p </Subscript> norm. A...</subscript>

In most western countries, there is a strong incentive for defence department budget-holders to expend all of the funds they are authorized to spend in a fiscal year. In this paper, we question whether this emphasis makes sense. We develop a model of a defence department's operating expenditure...

Public sector managers, particularly those at the highest level of government, tend to view lapsed (or unused) funds at the end of a fiscal year as a consequence of poor management and/or inadequate financial controls. The aim of this paper is to challenge this view. We show that the planning...