Susumu Yamasaki

A Framework for Adaptive e-Learning Systems in Higher Education with Information Visualization

E-learning systems have become important in higher education, especially in universities. An adaptive e-learning system, which dynamically generates suitable courses for each student, is one of the most remarkable research fields. In this paper, we propose a general framework for adaptive e-learning systems, and discuss the role of information visualization in adaptive e-learning systems.

A sound and complete procedure for a general logic program in non- floundering derivations with respect to the 3-valued stable model semantics

This paper presents a sound and complete procedure with respect to the 3-valued stable model semantics. The procedure is regarded as an extension of Eshghi and Kowalski abductive proof procedure, involving finite or countably infinite SLD resolution, as well as finite or countably infinite negative recursion caused by negation as failure. The procedure makes use of the set of negative literals (the set of abducibles) for the negation as failure to be implemented. The set of abducibles is not only applicable to the extraction of explanations for abduction as in Kakas et al. (J. Logic Comput. 2 (1992) 719-770) but also specified for what stable model is now computed in the procedure, because a 3-valued stable model is not always the least (that is, the well-founded model). The procedure also contains nondeterminism in the choices of what ground negative literals are used for negation as failure. By the assumptions of some adequate choices, the procedure is well-defined inductively. Copyright 2001 Elsevier Science B.V.

Soundness of abductive proof procedure with respect to constraint for non-ground abducibles

Abstract Eshghi and Kowalskis abductive procedure is not, in general, sound with respect to the 2-valued stable model semantics, but sound with respect to preferred extension (Dung, 1991). We establish an abduction framework in which the integrity constraint is defined so that nonground abducibles may be extracted. By dealing with alternating fixpoint theory as in Van Gelder (1993) on the domain containing variables, we show, with respect to the proposed constraint, the soundness of a modified version of Eshghi and Kowalskis procedure where the negation as failure with non-safe rule is adopted.

SLDNF resolution with non-safe rule and fixpoint semantics for general logic programs

The SLDNF resolution (SLD resolution with negation as failure) is often restricted to yield a safe rule, that is, negation as failure rule is adopted only in the case that the selected negative literal in each goal should be in ground. In this paper we investigate extensions of goals in SLDNF resolutions with the case of selecting non-ground negative literals. Since Shepherdsons proposal is thought of as most general [16, 18] we formally show how the success and failure sets by Sherpherdsons SLDNFS resolution are related with a fixpoint semantics, which is generalized to be concerned with atom sets involving the variables.

A calculus effectively performing event formation with visualization

As a programming technique, we formulate a calculus of illustrating event formation which is effectively performed. An event is visualized as a sequence of abstract charts denoting processes. The calculus contains a set of charts related to basic processes, a set of situations, a semantic function assigning a situation transition to each chart, a logic program with negation-as-failure, and the integrity constraint on the set of situations.

Visualization with hierarchically structured trees for an explanation reasoning system

This work is concerned with an application of drawing hierarchically structured trees. The tree drawing is applied to an explanation reasoning system. The reasoning is based on synthetic abduction (hypothesis) that gets a case from a rule and a result. In other words, the system searches a proper environment to get a desired result. In order that the system may be reliably related to the amount of rules which are used to get the answer, we visualize a process of reasoning to show how rules have concern with the process. Since the process of reasoning in the system makes a hierarchically structured tree, the visualization of reasoning is a drawing of a hierarchically structured tree. We propose a method of visualization that is applicable to the explanation reasoning system.

Recursion equation sets computing logic programs

Abstract This paper establishes a method of constructing a recursion equation set computing a given logic program. The recursion equation set is regarded as a dataflow program and transformable into a Lisp-like program for the dataflow. The recursion equation set constructible from a logic program expresses the procedure to form the minimal Herbrand model of the original logic program by means of inferences and is defined over a sequence domain. The domain is the set of all finite and infinite sequences of ground atoms. The recursion equation set contains functions corresponding to the inferences caused by definite clauses, and fair merge functions necessary for the purpose of taking set unions in terms of variables denoting ground atom sequences. The functions in accordance with the inferences concerning definite clauses areobtained by eliminating the nondeterminism usually involved. By the fair merge function, we mean a device to provide a sequence variable acquired by interleaving input infinite sequence variables without neglecting any part of any input sequence. It is shown that the recursion equation set defines a continuous function from a direct product of a sequence domain to itself, therefore there exists a least fixpoint of the function. The fixpoint completely denotes the minimal Herbrand model of the original logic program, which is essential for its finite computation. Finally it is shown that the recursion equation set can be expressed as a Lisp-like program.

Interaction with Computers Using Mobile Devices

We propose a new interaction way that uses mobile devices to input and output devices of computers. The idea is simple but powerful, because 1) mobile devices are popular, 2) people can use them easily, 3) people carry them at all times, 4) two displays one of which is a big display for a computer and another is a small display of a mobile device may make new interaction and visualization and 5) a user can store parts of public data in physically independent device, that is his/her mobile device. We expect that our idea may make psychological barrier lower than now so that users can access and modify all data around the world more easily. In this paper, we show an example application based the idea we propose and discuss its possibilities.

An Interactive Environment for Generating Sequential Information

We propose an interactive environment in which we can generate sequential information. Sequential information is a sequence of movements which makes changes of situations. The system allows a user to construct an environment for generating sequential information. We provide interactions and visualization for sequential information generation based on theoretical grounds

Logic programming with default, weak and strict negations

This paper looks at logic programming with three kinds of negation: default, weak and strict negations. A 3-valued logic model theory is discussed for logic programs with three kinds of negation. The procedure is constructed for negations so that a soundness of the procedure is guaranteed in terms of 3-valued logic model theory.