We believe that navigation in information spaces is best supported by tapping into our natural spatial and geographic ways of thinking. To this end, we are developing a new computer interface model called Pad. The ongoing Pad project uses a spatial metaphor for computer interface design. It provides an intuitive base for the support of such applications as electronic marketplaces, information services, and on-line collaboration. Pad is an infinite two-dimensional information plane that is shared among users, much as a network file system is shared. Objects are organized geographically; every object occupies a well defined region on the Pad surface. For navigation, Pad uses "portals" - magnifying glasses that can peer into and roam over different parts of this single infinite shared desktop; links to specific items are established and broken continually as the portal's view changes. Portals can recursively look onto other portals. This paradigm enables the sort of peripheral activity generally found in real phy...

Cooperative work typically involves both individual and group activities. Computer support for perspectives allows people to view and work in a central information repository within personal contexts. However, work in personal perspectives encourages divergent thinking. Negotiation in group perspectives is needed to converge on consensus, shared understanding, and cooperation. Negotiation processes on their own can delay progress. By intertwining perspective and negotiation mechanisms, individual results can be systematically merged into a group product while work continues. Personal perspectives on shared information are thereby intertwined and merged into a shared group understanding. WEBGUIDE is a prototype system that integrates perspective and negotiation mechanisms; its user interface has been mocked up in detail to work out the many issues involved. We have begun to use partial implementations of WEBGUIDE to support cooperative intellectual work in small research groups.

The web has greatly improved the accessibility of scientific information, however the role of the web in formal scientific publishing has been debated. Some argue that the lack of persistence of web resources means that they should not be cited in scientific research. We analyze references to web resources in computer science publications, finding that the number of web references has increased dramatically in the last few years, and that many of these references are now invalid. We also find that most invalid web references can be relocated easily. We argue that, while formal references to published articles should always be used when possible, web references help to improve communication and progress in science. However, citation practices need to be improved to minimize future loss. We provide recommended practices for citing web resources, and discuss methods for relocating invalid references.

Search engines like Google interpret links to a web page as objective, peer-endorsed and machine-readable signs of value. Links have become the currency of the Web. With this economic value they also have power, affecting accessibility and knowledge on the Web.

Non-standard database applications like CAD, CASE, or cooperative authoring systems impose new requirements on database management systems (DBMS). While object-oriented DBMS provide appropriate data modelling facilities they still lack adequate transaction management support for this kind of applications. Cooperative authoring processes are mainly characterized by long duration activities that are interactively performed bymultiple authors. They cooperate on shared documents to produce a final, commonly accepted, hyperdocument. Thus, a transaction model that is well-suited for suchanenvironment has to support long-running, interactively controlled activities, in which the competition for resources is replaced by the need to cooperate. In this paper, we present requirements for a cooperative transaction model to overcome the limitations of the traditional transaction model. The requirements are derived from the analysis of the cooperative hypermedia document authoring domain.

We present a general web-based information infrastructure capable of supporting the rapid development of highlyinteractive information environments that cater for widely varying requirements across application domains and all forms of fixed and mobile client devices. In particular, we describe how this infrastructure has been extended to support digitally augmented paper through a special transformation component that can map active areas of document pages to information objects so that user- and contextdependent interaction can be supported. Our infrastructure is sufficiently general and flexible to adapt to, not only emerging and even unanticipated technologies in the area of interactive paper, but also the rapidly expanding interaction sphere of hypermedia. 1

The World-Wide Web has greatly increased the number of hypermedia designers and practitioners -- the people who read and write, and otherwise use, hypermedia in their day-to-day activities. Through practice, they have developed new communicative forms: a set of hypermedia document genres. We examine the genres that are arising on the World-Wide Web as a foil for discussing the interaction between hypermedia design practice, hypermedia technology, and the types of hyperdocuments that evolve. The Web creates a particularly fertile environment for looking at such interactions, since the technology is familiar, examples abound, and evolution is rapid. Home pages on the World-Wide Web have arisen as a particular type of hypermedia document genre through an interplay of the constraints and a ordances of a particular constellation of technologies (the Internet, the Web, and HTML) and the needs and practices of on-line communities. The form is necessarily emergent, since there is no clear single predecessor for home pages, but rather a number of borrowed types, confounded by the characteristics of the

WebCrawler, the first comprehensive full-text search engine for the World-Wide Web, has played a fundamental role in making the Web easier to use for millions of people. Its invention and subsequent evolution, spanning a three-year period, helped fuel the Web's growth by creating a new way of navigating hypertext. Before search engines like WebCrawler, users found Web documents by following hypertext links from one document to another. When the Web was small and its documents shared the same fundamental purpose, users could find documents with relative ease. However, the Web quickly grew to millions of pages making navigation difficult. WebCrawler assists users in their Web navigation by automating the task of link traversal, creating a searchable index of the web, and fulfilling searchers’ queries from the index. To use WebCrawler, a user issues a query to a pre-computed index, quickly retrieving a list of documents that match the query. This dissertation describes WebCrawler's scientific contributions: a method for choosing a subset of the Web to index; an approach to creating a search service that is easy to use; a new way to rank search results that can generate highly effective results for both naive and expert searchers; and an architecture for the service that has effectively handled a three-order-of-magnitude increase in load. This dissertation also describes how WebCrawler evolved to accommodate the extraordinary growth of the Web. This growth affected WebCrawler not only by increasing the size and scope of its index, but also by increasing the demand for its service. Each of WebCrawler’s components had to change to accommodate this growth: the crawler had to download more documents, the full-text index had to become more efficient at storing and finding those documents, and the service had to accommodate heavier demand. Such changes were not only related to scale, however: the evolving nature of the Web meant that functional changes were necessary, too, such as the ability to handle naive queries from searchers.

World Wide Web (WWW) authors must cope in a hypermedia environment analogous to second-generation computing languages, building and managing all hypermedia links using simple anchors and single-step navigation. We present a set of third- and fouvth-generation hypermedia functionalities, which WWW developers should consider. We ground our discussion in the hypermedia research literature, and illustrate both from existing implementations and a running scenario. We also give some direction for implementing these on the WWW.

In the popular conception of hypertext as nonlinear writing, primary emphasis typically falls on the construction, character, and quantity of constituent lexias that comprise any given hypertext. This paper, however, will focus on what the text would reveal if an ordered collection were made of the links emerging from the main (first order) text. Such a collection, as a second order text or parallel text, which I propose to call the paratext, comprises the layerworld of links, of intertextual referents that could be subjected to cluster analyses that reveal aspects of cohesion, breadth, and other speculative characteristics of the first order text. KEYWORDS: Hypertext, intertextuality, link semantics, grammatology, paratext, rhetoric. INTRODUCTION This paper discusses the theme of augmenting possible understanding of a hypertext by applying an interpretive analysis of its links. The first part of the paper describes the concept and framework of the approach in critical terms. The se...