Abstract. We present PolyLens, a new collaborative filtering recommender system designed to recommend items for groups of users, rather than for individuals. A group recommender is more appropriate and useful for domains in which several people participate in a single activity, as is often the case with movies and restaurants. We present an analysis of the primary design issues for group recommenders, including questions about the nature of groups, the rights of group members, social value functions for groups, and interfaces for displaying group recommendations. We then report on our PolyLens prototype and the lessons we learned from usage logs and surveys from a nine-month trial that included 819 users. We found that users not only valued group recommendations, but were willing to yield some privacy to get the benefits of group recommendations. Users valued an extension to the group recommender system that enabled them to invite non-members to participate, via email.

. Collaborative authoring tools generate network effects, where each tool's value depends not just on the tool itself, but on the number of other people who also have compatible tools. We hypothesize that the best way to generate network effects and to add collaborative authoring capability to existing tools is to focus on the network protocol. This paper explores a protocol-centric approach to collaborative authoring by examining the requirements and functionality of the WebDAV protocol. Key features of the protocol are nonconnection -oriented concurrency control, providing an upward migration path for existing non-collaborative applications, support for remote manipulation of the namespace of documents, and simultaneous satisfaction of a wide range of functional requirements. Introduction Despite many compelling research examples of collaborative authoring, so far their impact on actual authoring practice has been limited. While BSCW (Bentley et al., 1997) and HYPER-G (Maurer, 1996...

Increasingly, documents exist primarily in digital form. System designers have recently focused on making it easier to read digital documents, with annotation as an important new feature. But supporting annotation well is difficult because digital documents are frequently modified, making it challenging to correctly reposition annotations in modified versions. Few systems have addressed this issue, and even fewer have approached the problem from the users' point of view. This paper reports the results of two studies examining user expectations for "robust" annotation positioning in modified documents. We explore how users react to lost annotations, the relationship between types of document modifications and user expectations, and whether users pay attention to text surrounding their annotations. Our results could contribute substantially to effective digital document annotation systems. Keywords Annotation, robust, digital, documents, annotation system design. 1 INTRODUCTION Four ...

this paper, we motivate, describe, and illustrate these requirements and our model. Introduction

Writing is a form of communication. Writing together is a process of negotiating for content and meaning of a text. Tools to support collaborative writing must take into consideration the communication which takes place both around and through the text. An extended field study of two groups of four grade six students was carried out to explore the impact of a shared text editor on communication and writing during synchronous collaborative writing. Analysis of the students ' interactions shows that a shared editor affects control of discourse, the pursuit of attention, and the development of the common ground essential for shared understanding between collaborating authors. These observations suggest that effective collaborative writing technology needs to satisfy design requirements in the areas of concurrency control, awareness, and shared task spaces. These design requirements were explored through the development of Calliope, a prototype synchronous collaborative writing tool built using the GroupKit groupware toolkit. iii Acknowledgments This thesis emerged from discussion and collaboration with a wide range of people. Ron Baecker, my supervisor, has been instrumental in keeping me interested in Computer Science over the past four years. Thanks for encouraging me to push the bounds (without breaking them), and for pushing me when I needed it... Janet Salaff, my second reader, introduced me to sociology and helped me write a thesis which deals with people, not just with computers. After all, without people, what’s the point? Ilona Posner was my collaborator on the Prejudice Project, and was responsible for most of the initial work. Her previous work on collaborative writing provided the inspiration for this thesis.

The collaborative editing of documents is a very common task nowadays. Writing groups are often distributed over many locations because of the globalization of organizations and the increasing interdisciplinarity of tasks. Since many writers already use computers for their jobs, providing computer support for the collaborative writing process has been identified as an important goal. Numerous tools for computer supported collaborative writing have already emerged but in most cases have not come into widespread usage. In this article the requirements of users for a collaborative editor are analyzed. Providing as much #exibility as possible to the users is identified as a basic need. According to the requirements summary a model for a group editing environmentis presented. The model covers cooperativework in local and wide area networks using synchronous and asynchronous cooperation. Finally, an application of the model is presented in the form of the multi-user editing environment IRIS.

models of information sharing, and runtime support based on those models, are by themselves incomplete for the task of constructing robust, practical collaborative applications. To be usable, we must provide a means for developers to access these facilities easily. This chapter has presented developer perspectives on the concepts introduced by Intermezzo. We have investigated a number of components of the developer support, or "toolkit," in this research, including notification, programming interfaces for accessing shared data, interfaces for accessing collaboration-specific functionality, and the use of scripting through embedded computation. Notification is one of the most important problems to be addressed in any developer support: how do applications (and, by extension, their users) become aware of changes in their environments? This problems is especially vexing in the case of coordination, where information that may be considered interesting is plentiful, change is rapid, and the...

As a promising approach to end-user computing, programming by demonstration (PBD) techniques have been explored by many researchers in single-user applications. This paper investigates how PBD techniques can be used to support end-user customization of groupware tools. In collaborative applications, complex semantic relationships can emerge unanticipatedly among objects (participants, data artifacts, tools, devices, etc.) such as the hierarchical organization of participants, consistency maintenance among different views of the same data, and awareness control. It is important that end users are empowered to customize the groupware application to model and enforce such relationships. We present an active rule based approach to modeling user-defined semantic relationships in collaborative applications and explore a demonstrational approach for end-user customization of collaboration tools to support the definition of those relationships. The presented work is based on our work on a shared whiteboard tool, CAB or Collaborative Active whiteBoard. Our approach is being generalized to support end-user defined object relationships in shared workspaces.

Annotations are a natural way to record comments and ideas in specific contexts within a document. When people read, they often underline important parts of a document or write notes in the margin. While we typically think of annotating paper documents, systems that support annotating digital documents are becoming increasingly common. Annotations on digital documents are easily shared among groups of people, making them valuable for a wide variety of tasks, including online discussion and providing feedback. This research explores three issues that arise when using annotations for asynchronous collaboration. First, I present the results of using a prototype annotation system, WebAnn, to support online discussions in an educational setting. In a field study in a graduate class, students contributed twice as much content to the discussion using annotations compared to a traditional bulletin board. Annotations also encouraged a different discussion style that focused on specific points in the paper being discussed. The study results suggest valuable improvements to the annotation system and factors to consider when incorporating online discussion into a class. Second, I examine providing appropriate notification mechanisms to support online discussion using annotations. After studying notifications in a large-scale commercial system and finding them lacking, I designed and deployed enhancements to the system. A field study of the new notifications found that overall awareness of annotation activity on software specifications increased with my enhancements. The study also found that providing more information in notification messages, supporting multiple communication channels through which notifications can be received, and allowing customization of notification messages ...

This paper reviews several user experiences researchers at the University of Arizona have had in building Internet-based tools to support collaborative writing. First, the technological framework for an advanced collaborative writing tool called Collaboratus is presented. Next, we review the tools that make up Collaboratus, and then provide an overview of the various user experiences we have had. Finally, many suggestions are provide for developing the next generation of collaborative writing tools. 1.0