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The bond portfolio problem is viewed as a multistage decision problem in which buy, sell, and hold decisions are made at successive (discrete) points in time. Normative models of this decision problem tend to become very large, particularly when its dynamic structure and the uncertainty of future interest rates and cash flows are incorporated in the model. In this paper we present a multiple period bond portfolio model and suggest a new approach for efficiently solving problems which are large enough to make use of as much information as portfolio managers can reasonably provide. The procedure utilizes the decomposition algorithm of mathematical programming and an efficient technique developed for solving subproblems of the overall portfolio model. The key to the procedure is the definition of subproblems which are easily solved via a simple recursive relationship.

PurposeThe purpose of this conceptual paper is to provide a typology for classification of the digital goods business (DGB), analyzing its characteristics with selected cases, to suggest an evolution strategy appropriate for today's digital business economy, and to address the research implications.Design/methodology/approachBased on a focus group interview, the study identified and classified the DGB models into four types in terms of sales channels and service methods, and further proposed five evolution strategies for the DGM.FindingsThe paper proposes five evolution strategies for the DGB: from streaming direct to streaming intermediary; from download direct to download intermediary; from download intermediary to streaming intermediary; from download direct to streaming direct; and from download direct to streaming intermediary. These evaluation strategies will be suitably applicable to the type of digital goods for which a business strives.Research limitations/implicationsAs the study is exploratory in nature, further research will be required to empirically confirm the findings of the underlying study regarding various DGBs, such as software, games, and movies. In addition, as the proposed typology reflects only the current state of the DGB industry, a further elaboration of the typology may also prove necessary in the future as technologies and the DGB industry evolve.Originality/valueProviding a useful theoretical foundation for future DGB studies and valuable insight into practical applications in the ever‐growing DGB field, the paper delivers transitional strategic insights based on digital goods taxonomy. This strategic implication can be applicable to analyzing and explaining current DGB cases.

This paper extends the well known results for linear fractional programming to the class of programming problems involving the ratio of nonlinear functionals subject to nonlinear constraints, where the constraints are homogeneous of degree one and the functionals are homogeneous of degree one to within a constant. Two rather general auxiliary problems are developed, and the relations between the solutions of the auxiliary problems and the solutions of the original problem are codified. Applications of the results for specific problems are also presented.