Doctoral Degrees (Computer Science)

Permanent URI for this collection

https://scholar.sun.ac.za/handle/10019.1/96338

Browse

Browsing Doctoral Degrees (Computer Science) by browse.metadata.advisor "Visser, Willem"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Using test data to evaluate rankings of entities in large scholarly citation networks
    (Stellenbosch : Stellenbosch University, 2019-04) Dunaiski, Marcel; Geldenhuys, J.; Visser, Willem; Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences. Division Computer Science.
    ENGLISH ABSTRACT : A core aspect in the field of bibliometrics is the formulation, refinement, and verification of metrics that rate entities in the science domain based on the information contained within the scientific literature corpus. Since these metrics play an increasingly important role in research evaluation, continued scrutiny of current methods is crucial. For example, metrics that are intended to rate the quality of papers should be assessed by correlating them with peer assessments. I approach the problem of assessing metrics with test data based on other objective ratings provided by domain experts which we use as proxies for peer-based quality assessments. This dissertation is an attempt to fill some of the gaps in the literature concerning the evaluation of metrics through test data. Specifically, I investigate two main research questions: (1) what are the best practices when evaluating rankings of academic entities based on test data, and (2), what can we learn about ranking algorithms and impact metrics when they are evaluated using test data? Besides the use of test data to evaluate metrics, the second continual theme of this dissertation is the application and evaluation of indirect ranking algorithms as an alternative to metrics based on direct citations. Through five published journal articles, I present the results of this investigation.
  • Thumbnail Image
    Item
    Verifying Android applications using Java PathFinder
    (Stellenbosch : Stellenbosch University, 2017-11-20) Botha, Heila-Marié; Visser, Willem
    ENGLISH ABSTRACT : Current dynamic analysis tools for Android applications do not achieve acceptable code coverage since they can only explore a subset of the behaviors of the applications and do not have full control over the environment in which they execute. In this work model checking is used to systematically and more effectively explore application execution paths using state matching and backtracking. In particular, we extend the Java PathFinder (JPF) model checking environment for Android. We describe the difficulties one needs to overcome as well as our current approaches to handling these issues. We obtain significantly higher coverage using shorter event sequences on a representative sample of Android apps, when compared to Dynodroid and Sapienz, the current state-of-the-art dynamic analysis tools for Android applications.