UWSpace

UWSpace is the University of Waterloo’s institutional repository for the free, secure, and long-term home of research produced by faculty, students, and staff.

Depositing Theses/Dissertations or Research to UWSpace

Are you a Graduate Student depositing your thesis to UWSpace? See our Thesis Deposit Help and UWSpace Thesis FAQ pages to learn more.

Are you a Faculty or Staff member depositing research to UWSpace? See our Waterloo Research Deposit Help and Self-Archiving pages to learn more.

Photo by Waterloo staff

Communities in UWSpace

Select a community to browse its collections.

Recent Submissions

  • Thumbnail Image
    Item type: Item ,
    Modeling and querying possible repairs in duplicate detection
    (University of Waterloo, 2009-06-29) Beskales, George; Soliman, Mohamed A.; Ilyas, Ihab F.; Ben-David, Shai
    One of the most prominent data quality problems is the existence of duplicate records. Current duplicate elimination procedures usually produce one clean instance (repair) of the input data, by carefully choosing the parameters of the duplicate detection algorithms. Finding the right parameter settings can be hard, and in many cases, perfect settings do not exist. Furthermore, replacing the input dirty data with one possible clean instance may result in unrecoverable errors, for example, identification and merging of possible duplicate records in health care systems. In this paper, we treat duplicate detection procedures as data processing tasks with uncertain outcomes. We concentrate on a family of duplicate detection algorithms that are based on parameterized clustering. We propose a novel uncertainty model that compactly encodes the space of possible repairs. We show how to efficiently support relational queries under our model, and allowing new types of queries on the set of possible repairs. We give an experimental study illustrating the scalability and the efficiency of our techniques in different configurations.
  • Thumbnail Image
    Item type: Item ,
    The presentation Maestro: Direct manipulation through gesture alone
    (University of Waterloo, 2009-03-18) Fourney, Adam; Terry, Michael; Mann, Richard
    Past research suggests a number of benefits to using hand-based interaction when interacting with electronic presentations. This paper introduces Maestro, a computer-vision based presentation system that uses hand gestures to allow fine-grained interaction with the contests of a projected slideshow. Maestro employs a single web camera and no other physical mediators. The contributions of this paper lie in robustly solving the gesture segmentation problem inherent in using only computer vision as input, and in a set of feedback mechanisms designed to scaffold use of the recognition system without interfering with the visual presentation of content. Specifically, Maestro employs bimanual cues, spatial and content based context, hand roles, and, in some case, dwell time to segment gestures. These strong segmentation cues are robust with respect to false positives and allows the actual gestures themselves to more directly match the action to be performed. They also result in a direct manipulation-style interface built on gestures alone. To assist with use, Maestro introduces a feedback comet, an augmented cursor that provides mnemonics for gestures and feedback to help govern gesture speeds to those conducive to gesture recognition. We present the design of the system and lessons learned from user evaluations.
  • Thumbnail Image
    Item type: Item ,
    Optimizing distributed XML queries through localization and pruning
    (University of Waterloo, 2009-04-06) Kling, Patrick; Ozsu, M. Tamer; Daudjee, Khuzaima
    Distributing data collections by fragmenting them is an effective way of improving the scalability of relational database systems. The unique characteristics of XML data present challenges that require different distribution techniques to achieve scalability. In this paper, we propose solutions to two of the problems encountered in distributed query processing and optimization on XML data, namely localization and pruning. Localization takes a fragmentation-unaware query plan and converts it to a distributed query plan that can be executed at the individual sites that hold XML data fragments in a distributed system. We then show how the resulting distributed query plan can be pruned so that only those sites are accessed that can contribute to the query result. We demonstrate that our techniques can be integrated into a real-life XML database system and that they significantly improve the performance of distributed query execution.
  • Thumbnail Image
    Item type: Item ,
    Equivalence of nested queries with mixed semantics (extended version)
    (University of Waterloo, 2009-03-13) DeHaan, David
    We consider the problem of deciding query equivalence for a conjunctive language in which queries output complex objects composed from a mixture of nested, unordered collection types. Using an encoding of nesting objects as flat relations, we translate the problem to deciding the equivalence between encodings output by relational conjunctive queries. This encoding equivalence cleanly unifies and generalizes previous results for deciding equivalence of conjunctive queries evaluated under various processing semantics. As part of our characterization of encoding equivalence, we define a normal form for encoding queries and content that this normal form offers new insight into the fundamental principles governing the behaviour of nested aggregation.
  • Thumbnail Image
    Item type: Item ,
    Representation of programming constructs with the kell-m calculus
    (University of Waterloo, 2009-03-09) Blanco, Rolando; Alencar, Paulo
    Kell-m is a new asynchronous, higher-order process calculus with localities, developed for modelling and verifying distributed event-based systems and applications. Although simple, due to the low level nature of kell-m, consideration effort is required when modelling complex systems. In this report we illustrate how common programming constructs such as variables, procedures, modules and lists can be represented using kell-m. These constructs facilitate the modelling of systems and applications using kell-m.