Management in the 1990s is an industry and governmental agency supported research program. Its aim is to develop a better understanding of the managerial issues of the 1990s and how to deal most effectively with them, particularly as these issues revolve around anticipated advances in Information Technology.Assisting the work of the Sloan School scholars with financial support and as working partners in research are: Much recent work on the Information Lens system has been done by Kum-Yew Lai, Ramana Rao, and David Rosenblitt. Kevin Crowston implemented and maintains the mail gateway between our system and the outside network world, Chee-Seng Chow helped implement the first version of the central mail sorter, and Constance Perin collaborated in some of the early studies of information sharing in organizations. We gratefully acknowledge all these contributions. SummaryAs it becomes both technically and economically feasible to send electronic messages and other documents to large numbers of possible recipients, the problem of deciding who should receive a particular piece of information will become increasingly important. This paper focuses on the application of techniques from artificial intelligence, user interface design, and organizational science to help people share interesting and relevant information without being inundated by the potentially vast amount of less useful information. Much of the work that has been done on computer-mediated communication systems, such as electronic mail, computer conferencing, and electronic bulletin boards, has focused on technical capabilities and standards for transporting and storing messages. In this paper, we propose to shift our focus to a more general problem that we will refer to as the information sharing problem. The information sharing problem involves disseminating information such that the information reaches those people to whom it is valuable and yet does not interfere with the information processing of people who will find no value in its contents.We argue that this problem will become increasingly important with advances in communication technology and we will suggest three fundamental approaches to its solution. Our characterization of these approaches will be illustrated with (1) examples from a series of informal studies that we have conducted on how people share information in organizations, and (2) a description of an intelligent information sharing system, called the Information Lens, that we have developed.It is already a common experience in mature computer-based messaging communities for people to feel flooded with large quantities of electronic "junk mail" [Den82; Pal84; Wil84; Hil85], and the increasing availability of inexpensive communication technology has the potential to overwhelm people with even more messages that are of little or no value to them. In current systems, people often adopt crude methods--such as removing themselves entirely from distribution lists that are of occasional interest--in order to avoid being inundated with informa...

We present a module calculus for studying a simple model of link-time compilation. The calculus is stratified into a term calculus, a core module calculus, and a linking calculus. At each level, we show that the calculus enjoys a computational soundness property: if two terms are equivalent in the calculus, then they have the same outcome in a smallstep operational semantics. This implies that any module transformation justified by the calculus is meaning preserving. This result is interesting because recursive module bindings thwart confluence at two levels of our calculus, and prohibit application of the traditional technique for showing computational soundness, which requires confluence. We introduce a new technique, based on properties we call lift and project, that uses a weaker notion of confluence with respect to evaluation to establish computational soundness for our module calculus. We also introduce the weak distributivity property for a transformation T operating on modules D 1 and D2 linked by ⊕: T (D1 ⊕ D2) = T (T (D1) ⊕ T (D2)). We argue that this property finds promising candidates for link-time optimizations.

Blocks-based programming has become the lingua franca for introductory coding. Studies have found that experience with blocks-based programming can help beginners learn more traditional text-based languages. We explore how blocks environments improve learnability for novices by 1) favoring recognition over recall, 2) reducing cognitive load, and 3) preventing errors. Increased usability of blocks programming has led to widespread adoption within introductory programming contexts across a range of ages. Ongoing work explores further reducing barriers to programming, supporting novice programmers in expanding their programming skills, and transitioning to textual programming. New blocks frameworks are making it easier to access a variety of APIs through blocks environments, opening the doors to a greater diversity of programming domains and supporting greater experimentation for novices and professionals alike.

We present λCIL, a typed λ-calculus which serves as the foundation for a typed intermediate language for optimizing compilers for higher-order polymorphic programming languages. The key innovation of λCIL is a novel formulation of intersection and union types and flow labels on both terms and types. These flow types can encode polyvariant control and data flow information within a polymorphically typed program representation. Flow types can guide a compiler in generating customized data representations in a strongly typed setting. Since λCIL enjoys confluence, standardization, and subject reduction properties, it is a valuable tool for reasoning about programs and program transformations.

Recent work has shown equivalences between various type systems and flow logics. Ideally, the translations upon which such equivalences are based should be faithful in the sense that information is not lost in round (1) it expresses call-string based polyvariance (such as k-CFA) as well as argument based polyvariance; (2) it enjoys a subject reduction property for flows as well as for types; and (3) it supports a flow-oriented perspective rather than a type-oriented one.