Wai-Shing Ho

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Traditional decision tree classifiers work with data whose values are known and precise. We extend such classifiers to handle data with uncertain information. Value uncertainty arises in many applications during the data collection process. Example sources of uncertainty include measurement/quantization errors, data staleness, and multiple repeated(More)
We study the problem of clustering uncertain objects whose locations are described by probability density functions (pdf). We show that the UK-means algorithm, which generalises the k-means algorithm to handle uncertain objects, is very inefficient. The inefficiency comes from the fact that UK-means computes expected distances (ED) between objects and(More)
Many kinds of real-life data exhibit logical ordering among their data items and are thus sequential in nature. However, traditional online analytical processing (OLAP) systems and techniques were not designed for sequence data and they are incapable of supporting sequence data analysis. In this paper, we propose the concept of Sequence OLAP, or S-OLAP for(More)
Cardiotocography (CTG) is a simultaneous recording of fetal heart rate (FHR) and uterine contractions (UC). It is one of the most common diagnostic techniques to evaluate maternal and fetal well-being during pregnancy and before delivery. By observing the Cardiotocography trace patterns doctors can understand the state of the fetus. There are several signal(More)
OBJECTIVES To compare surgical outcome both radiologically and clinically after interventions for patients with Moyamoya disease. METHODS This retrospective observational study included 25 patients who were treated surgically for Moyamoya disease in the past 14 years. Clinical outcomes were analyzed by subgroups stratified by age, disease presentation,(More)
Organization of a web site is important to help users get the most out of the site. A good web site should help visitors nd the information they want easily .Visitors typically nd information by searc hing for selected terms of interest or b y follo wing links from one w eb page to another.The rst approach is more useful if the visitor knows exactly what he(More)
We investigate the problem of frequent itemset mining over a data stream with bursty traffic. In many modern applications, data arrives at a system as a continuous stream of transactions. In many cases, the arrival rate of transactions fluctuates wildly. Traditional stream mining algorithms, such as Lossy Counting (LC), were generally designed to handle(More)
Sequence data processing has been studied extensively in the literature. In recent years, the warehousing and online-analytical processing (OLAP) of archived sequence data have received growing attentions. In particular, the concept of sequence OLAP is recently proposed with the objective of evaluating various kinds of so-called Pattern-Based Aggregate(More)
Mobile devices are capable of retrieving and processing data from remote databases. In a wireless data transmission environment, users are typically charged by the size of transferred data, rather than the amount of time they stay connected. We propose algorithms that join information from non-collaborative remote databases on mobile devices. Our methods(More)
Given a set of products, where each is characterized by a set of attribute values, an online catalog is an organization of a set of product pages on the web through which users can access their required product information. A good online catalog is crucial to the success of an e-commerce web site. Traditionally, an online catalog is mainly built by hand. To(More)