RESEARCH PROGRESS IN MIS: THE CENTER FOR RESEARCH ON INFORMATION SYSTEMS NEW YORK UNIVERSITY

Information Systems Working Papers Serie

USER INTERFACES FOR DECISION SUPPORT SYSTEMS: AN OVERVIEW

Information Systems Working Papers Serie

INFORMATION GAMES IN THE QUEST FOR MINDSHARE

The rapid growth and great popularity of Internet sites that specialize in providing intangible services in the form of information and community services gives rise to new forms of competition. Information Web sites such as www.how2.com and community sites such as www.iVillage.com provide free "content" and rely on advertising and hosting revenues to generate income. The competition between content sites in the same market niche is intense and only a few companies are likely to survive. In this paper, we examine a number of competitive models or "information games" that provide insights into the nature of this competition. The models capture differences between the type and maturity of the markets and differences in the behavioral assumptions about the nature of consumer demand for content. While these markets often have a "winner-takes-all" nature, we find a number of situations in which more than one player can survive at equilibrium.Information Systems Working Papers Serie

LANGUAGES FOR DECISION SUPPORT SYSTEMS: AN OVERVIEW

In this paper we survey some issues relating to the language interfaces provided by DSS. We do this from the point-of-view of the designer of generalized software for building DSS. We first describe a fairly general architecture for such software. This is followed by a brief examination of the language interface components. We list the functions that must be provided through the language facilities of a DSS together with a number of implementation issues such as User-friendliness, degree of procedurality and interpretation versus compilation. This provides a useful framework for the comparative evaluation of DSS packages. Finally we discuss some possible directions for future development including specialized formal languages and the potential of English-like 'semi-natural' languages.Information Systems Working Papers Serie

AN INTELLIGENT SYSTEM FOR FORMULATING LINEAR PROGRAMS

The research and system development work described in this paper is aimed at overcoming some of the problems associated with the development of large, complex linear programming problems. The most overwhelming problem is that of size. It is not uncommon for large planning and policy analysis problems to have tens of thousands of constraints and activities. Matrix generator systems have been designed to help in this process. However, the amount of manual labor involved is still very great and the formulation process is subject to errors which are difficult to detect. We provide an overview of a system which uses artificial intelligence and database techniques to help a knowledgeable user formulate large linear programs. The system automates many of the tedious processes associated with large-scale modeling and provides a top-down development environment with a number of different forms of problem representation.Information Systems Working Papers Serie

REPRESENTATION SCHEMES FOR MATHEMATICAL PROGRAMMING MODELS

Because of the difficulties often experienced in formulating and understanding large scale models, much current research is directed towards developing systems to support the construction and understanding of management science models. This paper discusses seven different methods for representing mathematical programming models during the formulation phase of the modeling process. The approaches discussed are block-schematic, algebraic, three different kinds of graphical schemes, a database-oriented approach and Structured Modeling. We emphasize representations that have graphical elements suitable for incorporation in the interface to a modeling system. The different methods are compared using a common example and the transformations that allow one to go from one representation to another are discussed.Information Systems Working Papers Serie

REPRESENTATION SCHEMES FOR MATHEMATICAL PROGRAMMING MODELS

Because of the difficulties often experienced in formulating and understanding large scale models, much current research is directed towards developing systems to support the construction and understanding of management science models. This paper discusses six different methods for representing mathematical programming models during the formulation phase of the modeling process. The approaches discussed in the paper include algebra, three different kinds of graphical schemes, a database-oriented approach and Structured Modeling. We emphasize representations that have graphical elements suitable for incorporation in the interface to a modeling system. The different methods are compared using a common example and conclusions are drawn as to their suitability for various modeling tasks and situations.Information Systems Working Papers Serie

X-Ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu

We have used a MHz lock-in x-ray spectro-microscopy technique to directly detect changes of magnetic moments in Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x-rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of $3\times 10^{-5}$ $\mu_\mathrm{B}$ on Cu atoms within the bulk of the 28 nm thick Cu film due to spin-accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments on Cu interface atoms are transiently increased by about 10% or $4\times 10^{-3}$ $\mu_\mathrm{B}$. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow

COMPOSITION RULES FOR BUILDING LINEAR PROGRAMMING MODELS FROM COMPONENT MODELS

This paper describes some rules for combining component models into complete linear programs. The objective is to lay the foundations for systems that give users flexibility in designing new models and reusing old ones, while at the same time, providing better documentation and better diagnostics than currently available. The results presented here rely on two different sets of properties of LP models: first, the syntactic relationships among indices that define the rows and columns of the LP, and second, the meanings attached to these indices. These two kinds of information allow us to build a complete algebraic statement of a model from a collection of components provided by the model builder.Information Systems Working Papers Serie

LPSPEC: A Language for Representing Linear Programs

Information Systems Working Papers Serie