Richard Furuta

Digital libraries

ing Education-support Object-oriented Accessibility Electronic publishing OCR Agents Ethnographic study OODB support Annotation Filtering Personalization Archive Geographic information system Preservation Billing, charging Hypermedia Privacy Browsing Hypertext Publisher library Catalog Image processing Repository Classification Indexing Scalability Clustering Information retrieval Searching Commercial service Intellectual property rights Security Content conversion Interactive Sociological study Copyright clearance Knowledge base Storage Courseware Knowbot Standard Database Library science Subscription Diagrams (e.g., CAD) Mediator Sustainability Digital video Multilingual Training support Discipline-level library Multimedia stream playback Usability Distributed processing Multimedia systems Virtual (integration) Document analysis Multimodal Visualization Document model National library World-Wide Web Economic study Navigation its characterization of digital libraries. Many important projects and perspectives have been omitted. Here we give some pointers to aid further exploration, and of course we encourage interested readers to attend the numerous conferences and workshops scheduled in this field, many sponsored by or in cooperation with ACM and its SIGs. One early journal special issue is introduced in [6]. It includes articles on copyright and intellectual property rights, a subscription model for handling funds transfer related to digital libraries, a description of the evolution of the WAIS search system in general and its interfaces in particular, an overview of the Right Pages system and its use of OCR and document analysis algorithms, and an early overview of the Envision system [7]. We note that to many, intellectual property rights issues and ways to obtain revenue streams to sustain digital libraries are the most important open problems. The largest digital library conference makes its proceedings available over the WWW [9]. These contain many insightful discussions, proposals of new research ideas, descriptions of base technologies, and explanations of how the broad concept of a digital library fits in with the needs of specific user communities and the information they require. Readers can find a variety of works on agents, architectures, catalogs, collaboration, compression, document analysis from OCR and page images, document structure, electronic journals, heterogeneous sources, knowledge-based approaches, library science, numerical data collections, object stores, and organizational usability. For more details on the origins of the Digital Library Initiative, and for a variety of perspectives on open research problems, we refer the reader to [5]. This work also has numerous pointers to people, projects, institutions, and other reference works in the area. For a perspective on the role the computer industry should have in this field, see [10]. This report outlines IBM’s perspective on key supporting technologies and on the unique challenges highlighted by the emergence of digital libraries. We expect considerable interest from the corporate sector as well as from government agencies in this important area of information technology. For lack of space, we have had to omit many publications on networking and storage technologies, sociological and ethnographic studies, library and information science, OCR and document analysis or conversion, and rights management. These and other works are needed to round out the discussion of digital libraries. However, we encourage you to read the rest of this issue as a good starting point for your future studies of this important field. We invite you to not only use but also help in the creation of a future World Digital Library System!

Petri-net-based hypertext: document structure with browsing semantics

We present a formal definition of the Trellis model of hypertext and describe an authoring and browsing prototype called αTrellis that is based on the model. The Trellis model not only represents the relationships that tie individual pieces of information together into a document (i.e., the adjacencies), but specifies the browsing semantics to be associated with the hypertext as well (i.e., the manner in which the information is to be visited and presented). The model is based on Petri nets, and is a generalization of existing directed graph-based forms of hypertext. The Petri net basis permits more powerful specification of what is to be displayed when a hypertext is browsed and permits application of previously developed Petri net analysis techniques to verify properties of the hypertext. A number of useful hypertext constructs, easily described in the Trellis model, are presented. These include the synchronization of simultaneous traversals of separate paths through a hypertext, the incorporation of access controls into a hypertext (i.e., specifying nodes that can be proven to be accessible only to certain classes of browsers), and construction of multiple specialized (tailored) versions from a single hypertext.

Hypertext paths and the World-Wide Web: experiences with Walden's Paths

Walden’s Paths applies the concept of hypertextual paths to the World-Wide Web. Walden’s Paths is being developed for use in the K–12 school environment. The heterogeneity of the Web coupled with the desirability of supporting the teacher-student relationship make this an interesting and challenging project. We describe the Walden’s Paths implementation, discuss the elements that affected its design and architecture, and report on our experiences with the system in use.

Toward Virtual Community Knowledge Evolution

This paper puts forth a vision and an architecture for a community knowledge evolution system. We propose augmenting a multimedia document repository (digital library) with innovative knowledge evolution support, including computer-mediated communications, community process support, decision support, advanced hypermedia features, and conceptual knowledge structures. These tools, and the techniques developed around them, would enable members of a virtual community to learn from, contribute to, and collectively build upon the communitys knowledge and improve many member tasks. The resulting Collaborative Knowledge Evolution Support System (CKESS) would provide an enhanced digital library infrastructure serving as an ever-evolving repository of the communitys knowledge, which members would actively use in everyday tasks and regularly update.

The virtual panel architecture: A 3D gesture framework

The Virtual Panel Architecture (VPA) has been designed to help implement an intermediate abstraction with elements of both a physical control panel and a computer-based control panel. This abstraction, handling 3D point-based gesticulative interaction with modeled object hierarchies, is suitable for both virtual reality environments and traditional environments. Based on the VPA, an environment of virtual panels is demonstrated which can be incorporated into keyboard-and-mouse-based computing. Users are able to turn virtual knobs, adjust virtual sliders, and point at virtual screens on these virtual panels in this environment.<<ETX>>

Hyperdocuments as automata: verification of trace-based browsing properties by model checking

We present a view of hyperdocuments in which each document encodes its own browsing semantics in its links. This requires a mental shift in how a hyperdocument is thought of abstractly. Instead of treating the links of a document as defining a static directed graph, they are thought of as defining an abstract program, termed the links-automaton of the document. A branching temporal logic notation, termed HTL*, is introduced for specifying properties a document should exhibit during browsing. An automated program verification technique called model checking is used to verify that browsing specifications in a subset of HTL* are met by the behavior defined in the links-automation. We illustrate the generality of these techniques by applying them first to several Trellis documents and then to a Hyperties document.

Metadata visualization for digital libraries: interactive timeline editing and review

Interactive Timeline Editing and Review (ITER), a general framework for modeling and presenting temporal information, is described. In addition, the tmViewer interface is described for viewing temporal and other metadata. ITER and tmViewer go beyond previous electronic timeline displays in treating timelines as h y pertexts and structured documents, and allowing interactive display of the metadata in addition to the events. The use of the tool is described for exploring bibliographic records, such as search hits from the book database available at amazon.com, and for the presentation of timelines.

Programmable browsing semantics in Trellis

In this report we outline a technique by which a hypertext system can offer flexible, programmable browsing behavior, or browsing semantics. Differences in the way documents are to be browsed can be specified by an author on a document-by-document basis, or by a style designer for an entire class of documents. The ability to specify and modify how a browser presents information is an important and useful property in general. We first discuss the issues involved in programmable browsing semantics, and then we present one method of providing them within the context of the Trellis project at the University of Maryland.

Dynamic adaptation of hypertext structure

A technique is described for adapting the apparent structure of a hypertext to the behavior and preferences exhibited by its users while browsing. Examples are given an implementation of this technique using the timing mechanism in Trellis. In the technique, event durations in a document are altered without actually changing the links in the underlying Petri net. The two extrema of instantaneous events and infinite delays can be used to create apparent node and link deletions and additions, as well as to insert new tokens (loci of activity) into a document. Adaptation of these times is accomplished using a simple data state in which the event timings (and other document properties) are variables, called attributes. As a reader traverses hypertext links, author-supplied aulzptation agents are invoked to collect information and possibly change the values of the attributes. Agents encapsulate and effect the criteria for deciding when, and specifically how, a structure should be adapted. Several practical examples illustrate the conclusion of this repofi sophisticated alterations do not require a complicated adaptation mechanism, that changing document constants into document variables provides flexibility to this mechanism, and that using a limited simple mechanism is the only hope for retaining analysis of the static and dynamic net properties.

Temporal hyperprogramming

The visual programming aspects of Trellis hypertext documents are described. A hypertext is a non-linearly organized, browsable information structure. The importance of browsing distinguishes hypertext from other network information systems. The possible experiences a user may have when interacting with a hypertext are as important as its form. Further, these browsing semantics should be an inherent characteristic of a document, not of the implementation that allows browsing. In essence, a hypertext is an active entity that has a visible behavior, not a static entity that is manipulated by external means. The Trellis model employs the dual nature of Petri nets to formally express both aspects of a hypertext in one structure. A Petri net is a bipartite graph, so it captures the linked structure of relationships among information elements. It is also an automaton, having an execution state and state transition rules, thereby formally capturing the interactions between reader and document. In this report, we define the temporal semantics of the Trellis model and illustrate them with a prototype hypertext system called @aTrellis. This environment joins timed events and active computing engines into a dynamic, parallel browsing structure. In @aTrellis, hypertext authoring is visual programming for a temporally-synchronized, visual outcome-temporal hyperprogramming.