Browsing by Author "Witten, Ian H"

Now showing 1 - 7 of 7
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    ACCELERATING SEARCH IN FUNCTION INDUCTION
    (1989-11-01) Phan, Thong H.; Witten, Ian H
    Inducing functions from examples is an important requirement in many learning systems. Blind search is the most general approach, but is vastly less efficient than specialized problem-solving methods. This paper presents a new strategy to accelerate search without sacrificing generality. Experiments with numeric functions show several orders of magnitude performance increase over the standard search technique. Two factors account for this improvement. First, the new strategy manipulates functions in groups instead of singly, so that many can be selected or discarded with only one comparison. Second, functional equivalence is handled automatically by the internal organization of search space.
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    DIRECTING THE USER INTERFACE: HOW PEOPLE USE COMMAND-BASED COMPUTER SYSTEMS
    (1988-01-01) Witten, Ian H; Greenberg, Saul
    Several striking and surprising characteristics of how people use interactive systems are abstracted from a large body of recorded usage data. In particular, we examine frequencies of invocation of commands and complete command lines (including modifiers and arguments), as well as vocabulary growth. Individual differences are of particular interest, and the results are analyzed by user and by identifying groups of like users. The study underlines the remarkable diversity that exists even within groups having apparently similar needs.
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    Generating advice by monitoring user behaviour
    (1985-06-01) Zissos, Adrian Y; Witten, Ian H
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    THE REACTIVE KEYBOARD: A PREDICTIVE TYPING AID
    (1989-11-01) Darragh, John J.; Witten, Ian H; James, Mark L.
    The Reactive Keyboard is a device that accelerates typewritten communication with a computer system by predicting what the user is going to type next. Text is entered by pointing into a menu of predictions. Predictions are based on a model of language that is created adaptively and updated continually as new text is entered. This new interface has great potential to enhance the ease and rate of communication, especially for physically limited people.
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    SUPPORTING COMMAND REUSE: EMPIRICAL FOUNDATIONS AND PRINCIPLES
    (1989-12-01) Witten, Ian H; Greenberg, Saul
    Current user interfaces fail to support some work habits that people naturally adopt when interacting with general-purpose computer environments. In particular, users frequently and persistently repeat their activities (eg command lines, menu selections), but computers do little to help them to review and re-execute earlier ones--at most providing ad hoc "history mechanisms" founded on the premise that the last few inputs form a reasonable selection of candidates for re-use. This paper provides theoretical and empirical foundations for the design of a general facility that helps people to recall, modify and re-submit their previous activities to computers. It abstracts several striking characteristics of repetition behaviour from usage data gleaned from many users of different systems. It presents a general model of interaction called recurrent systems. Particular attention is paid to the repetition of command lines given a sequential "history list" of previous ones, and this distribution can be conditioned in several ways to enhance predictive power. Reformulated as empirically-based general principles, the model provides design guidelines for reuse facilities specifically and modern user interfaces generally. A brief case study of actual use of a widely-available history system is included.
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    A SURVEY OF REUSE FACILITIES
    (1989-12-01) Witten, Ian H; Greenberg, Saul
    Reuse facilities help people to recall and modify their earlier activities and re-submit them to the computer. This paper surveys existing reuse facilities under three main headings: history mechanisms, adaptive systems, and programming by example. The first kind relies on temporally ordered lists of interactions, the second builds abstract models of past activities and uses them to expedite future interaction, while the third collects and generalizes more extensive sequences of activities for future reuse. A companion paper (Greenberg & Witten, 1989) presents the results of a large-scale study of how users actually repeat their activities on computers and contrasts the multitude of opportunities for reuse with the relatively infrequent use of an actual history mechanism.
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    User modeling for a computer coach: a case study
    (1985-06-01) Zissos, Adrian Y; Witten, Ian H