Luis Francisco-Revilla

Managing change on the web

Increasingly, digital libraries are being defined that collect pointers to World-Wide Web based resources rather than hold the resources themselves. Maintaining these collections is challenging due to distributed document ownership and high fluidity. Typically a collections maintainer has to assess the relevance of changes with little system aid. In this paper, we describe the Waldens Paths Path Manager, which assists a maintainer in discovering when relevant changes occur to linked resources. The approach and system design was informed by a study of how humans perceive changes of Web pages. The study indicated that structural changes are key in determining the overall change and that presentation changes are considered irrelevant.

Adaptive medical information delivery combining user, task and situation models

Medical information delivery for users with different levels of expertise will be required for the manned mission to Mars due to limited potential for communication with Earth. The Mars Medical Assistant (MMA) uses a combination of user, situation, and task models to create virtual hypertext structures by piecing together medical “information components.” Information components are chosen based on the semantic content and the cognitive characteristics of the components media type. The medical assistant currently supports three tasks: 1) describing medical procedures, 2) aiding diagnosis, and 3) providing information on health concerns. Conflicting suggestions from the three models need to be resolved. Tradeoffs in the model representations and conflict resolution strategies are being explored in the context of MMA.

Managing distributed collections: evaluating Web page changes, movement, and replacement

Distributed collections of Web materials are common. Bookmark lists, paths, and catalogs such as Yahoo! Directories require human maintenance to keep up to date with changes to the underlying documents. The Waldens paths path manager is a tool to support the maintenance of distributed collections. Earlier efforts focused on recognizing the type and degree of change within Web pages and identifying pages no longer accessible. We now extend this work with algorithms for evaluating drastic changes to page content based on context. Additionally, we expand on previous work to locate moved pages and apply the modified approach to suggesting page replacements when the original page cannot be found. Based on these results we are redesigning the path manager to better support the range of assessments necessary to manage distributed collections.

Perception of content, structure, and presentation changes in Web-based hypertext

The Web provides access to a wide variety of information but much of this information is fluid; it changes, moves, and occasionally disappears. Bookmarks, paths over Web pages, and catalogs like Yahoo! are examples of page collections that can become out-of-date as changes are made to their components. Maintaining these collections requires that they be updated continuously. Tools to help in this maintenance require an understanding of what changes are important, such as when pages no longer exist, and what changes are not, such as when a visit counter changes. We performed a study to look at the effect of the type and quantity of change on peoples perception of its importance. Subjects were presented pairs of Web pages with changes to either content (e.g., text), structure (e.g., links), or presentation (e.g., colors, layout). While changes in content were the most closely connected to subjects perceptions of the overall change to a page, subjects indicated a strong desire to be notified of structural changes. Subjects only considered the simultaneous change of many presentation characteristics as important.

WARP: a web-based dynamic spatial hypertext

WARP is a Web-based dynamic spatial hypertext that runs in a Web browser. WARP includes the ability to transclude other spatial hypertexts as collections. WARP also enables annotation and other content manipulation to be preserved in personal reading sessions. WARP uses a variety of presentation adaptations to contextualize the spatial hypertexts display. In particular WARP uses a variable number of models to guide adaptation in response to multiple relevant factors. Behaviors in WARP help preserve perceptual structures that may be lost due to adaptation and user interaction.

Browsing intricately interconnected paths

Graph-centric and node-centric browsing are the two commonly identified hypertext-browsing paradigms. We believe that path-centric browsing, the browsing behavior exhibited by path interfaces, is an independent browsing paradigm that combines useful aspects of the two commonly supported cases. Paths have long been recognized as an effective medium for aggregating and communicating information and have been included in various hypermedia systems as alternate metaphors or supporting tools. The Waldens Paths project promotes path-centric traversal as the primary browsing mechanism over Web-based materials. This paper expands the notion of our paths to include more generalized structures and interconnections across paths. We present an architecture for describing complex networks of such paths. Finally, we discuss the design and present a prototype implementation of the Path Engine, a tool that provides a linear interface for browsing intricately interconnected paths.

Interpreting the layout of web pages

Web pages such as news and shopping sites often use modular layouts. When used effectively this practice allows authors to present clearly large amounts of information in a single page. However, while sighted people can visually parse and understand these complex layouts in seconds, current assistive technologies such as screen readers cannot. This puts visually impaired users at a great disadvantage. In order to design better assistive technologies, we conducted a study of how people interpret modular layouts of news and shopping Web pages. The study revealed that when the layout complexity increases, the interpretation process gets longer and the reading gets more varied. Also, before looking at the main content, users first frame the Web page by looking for familiar structural elements that can be used as references and entry points. These elements include navigational bars, search boxes, and ads. This implies that assistive technologies can reduce the time required to frame the pages if they help users identify reference points and entry points.

Interpretation of web page layouts by blind users

Digital libraries must support assistive technologies that allow people with disabilities such as blindness to use, navigate and understand their documents. Increasingly, many documents are Web-based and present their contents using complex layouts. However, approaches that translate two-dimensional layouts to one-dimensional speech produce a very different user experience and loss of information. To address this issue, we conducted a study of how blind people navigate and interpret layouts of news and shopping Web pages using current assistive technology. The study revealed that blind people do not parse Web pages fully during their first visit, and that they can miss important parts. The study also provided insights for improving assistive technologies.

Longitudinal study of changes in blogs

Web-based distributed collections often include links to documents that are expected to change frequently, such as blogs. The study reported here demonstrates that blog changes follow specific patterns. The results also illustrate the substantial role of standardized templates in blog pages. These results extend our earlier models that assess the significance of Web page change from a human perspective. These improved models will enable software systems to assist human collection managers in identifying unexpected changes and aberrant events.

Dynamically growing hypertext collections

Many approaches have been pursued over the years to facilitate creating, organizing, and sharing collections of materials extracted from large information spaces. Little attention, in the context of hypertext collections, has been paid to the addition of new materials to these collections over time. Traditionally, human maintainers manually incorporate new materials into existing collections as they appear in the underlying network. In this paper we address the issues involved in supporting the creation and maintenance of dynamically growing hypertextual collections. We describe a prototype implementation for automatically including additional, relevant materials into Web-based collections. Our prototype uses the metaphor of hypertextual paths, a proven technique for layering metastructure atop existing hypertextual materials, which is particularly well suited to accommodating growing collections.