Wai Mok

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A Normal Form Redundancy in for Precisely Characterizing

We givea straightforward definition for redundancy in individual nested relations and define a ne... more We givea straightforward definition for redundancy in individual nested relations and define a new normal form that precisely characterizes redundancy for nested relations. We base our definition of redundancy on an arbitrary set of functional and multivalued dependencies, and show that our definition of nested normal form generalizes standard relational normalization theory. In addition, we give a condition that can prevent an unwanted structural anomaly in nested relations, namely, embedded nested relations with at most one tuple, Like other normal forms, our nested normal form can serve as a guide for database design.

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Corrigendum: "Designing Redundancy-Free XML Schema : A Smallest Closure Approach

International Journal of Cooperative Information Systems, Mar 1, 2016

The name of the first author was listed as Wai Yan Mok in the article published on 12 October 201... more

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A Feasible Schema Design Strategy for Amazon DynamoDB: A Nested Normal Form Approach

2020 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM), 2020

Amazon DynamoDB is a next-gen NoSQL (Not only SQL), key-value and document database that delivers... more Amazon DynamoDB is a next-gen NoSQL (Not only SQL), key-value and document database that delivers single-digit millisecond performance at any scale. As more complex web-based applications adopt DynamoDB, it is imperative to develop sound design strategies for DynamoDB schemas. Large-scale web-based applications often exhibit conflicting requirements. Hence, the research problem is to design the DynamoDB schemas of a given application with conflicting requirements such that the database must satisfy certain predetermined performance goals. In the era of relational databases, normal forms were developed to guide the schema design process. Past knowledge and experiences, we believe, are also applicable to DynamoDB schema design. Specifically, based upon Nested Normal Form and XML databases, this paper demonstrates the feasibility of a design strategy on DynamoDB schemas, particularly with the access patterns of the data in mind. Simulation further substantiates the feasibility of our approach.

Maximizing control flow concurrency in BPMN workflow models through syntactic means

Business Process Management Journal, 2018

Purpose Concurrency is a desirable property that enhances workflow efficiency. The purpose of thi... more Purpose Concurrency is a desirable property that enhances workflow efficiency. The purpose of this paper is to propose six polynomial-time algorithms that collectively maximize control flow concurrency for Business Process Model and Notation (BPMN) workflow models. The proposed algorithms perform model-level transformations on a BPMN model during the design phase of the model, thereby improving the workflow model’s execution efficiency. Design/methodology/approach The approach is similar to source code optimization, which solely works with syntactic means. The first step makes implicit synchronizations of interdependent concurrent control flows explicit by adding parallel gateways. After that, every control flow can proceed asynchronously. The next step then generates an equivalent sequence of execution hierarchies for every control flow such that they collectively provide maximum concurrency for the control flow. As a whole, the proposed algorithms add a valuable feature to a BPMN ...

Workflow re-engineering through introduction of concurrency

2014 Science and Information Conference, 2014

Making use of the concepts of the activity diagrams of the Unified Modeling Language, this paper ... more Making use of the concepts of the activity diagrams of the Unified Modeling Language, this paper defines an important class of workflows, called flow independent workflows, which are deterministic in the sense that if a flow independent workflow is given the same multi-set of resources as input over and over again, it will produce the same output every time. After which, this paper provides a methodology, and its accompanying algorithms, that introduces concurrency to flow independent workflows by rearranging the action nodes in every flow of control. It then applies the methodology to a real-world case to demonstrate its usefulness. It concludes with future research possibilities that might extend the methodology to general workflows, i.e., not necessarily flow independent workflows.

Extracting Relevant Sentences from Past Court Decisions: An Important First Step of A Legal Deep Learning Research Project

International Journal of Knowledge Engineering, 2018

This paper presents a potential solution to the problem of extracting relevant sentences from pas... more This paper presents a potential solution to the problem of extracting relevant sentences from past court decisions, which is an important first step of our legal deep learning research project. Court decisions are typically written in natural language like English. Hence, our extraction solution first uses legal statutes to construct an ontology for the desired sentences, and then uses NLTK (Natural Language Toolkit), a Python Natural Language Processing Toolkit, to construct search patterns based on the ontology to extract relevant passages from hundreds or thousands of past court decisions. The extracted sentences will be further processed and the resulting information will then be fed into a deep learning system, whose purpose is to assist legal practitioners by selecting relevant documents and streamline litigation.

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Classification of Breach of Contract Court Decision Sentences

This research project develops a methodology to utilize machinelearning analysis of live disputes... more This research project develops a methodology to utilize machinelearning analysis of live disputes to assist legal professionals in narrowing issues and comparing relevant precedents. An important part of this research project is an ontology of target court decisions, which is first constructed from relevant legal statutes, probably assisted by human legal experts. Utilizing the ontology, we extract and classify sentences in court decisions according to type. Since court decisions are typically written in natural languages, such as English and Chinese, chosen court decisions are pre-processed with the Natural Language Processing library spaCy, and then fed into the machine learning component of the system to extract and classify the sentences of the input court decisions.

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A Security Price Data Cleaning Technique: Reynold’s Decomposition Approach

Communications in Computer and Information Science, 2017

We propose a security price data cleaning technique based on Reynold's decomposition that uses T ... more We propose a security price data cleaning technique based on Reynold's decomposition that uses T 0 (the time period of integration) to determine the de-noise level of the price data. The goal of this study is to find the optimal T 0 that reveals an underlying price trend, possibly indicating the intrinsic value of the security. The DJIA (Dow Jones Industrial Average) Index and the thirty companies comprising the index are our fundamental interest. Preliminary results suggest that the graphs of ↵ (a key percentage measure) versus T 0 of the thirty companies and the DJIA Index exhibit at least two properties: (1) ↵ drops exponentially as T 0 increases when T 0 / order of magnitude of 100 days, and (2) ↵ drops linearly as T 0 increases when T 0 ' order of magnitude of 100 days. For the DJIA Index itself, T 0 is less than order of magnitude of 100 days. The result of applying our technique to each component stock of the DJIA parallels the result of the technique applied to the DJIA Index itself.

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Utilizing Nested Normal Form to Design Redundancy Free JSON Schemas

International Journal of Recent Contributions from Engineering, Science & IT (iJES), 2016

JSON (JavaScript Object Notation) is a lightweight data-interchange format for the Internet. JSON... more JSON (JavaScript Object Notation) is a lightweight data-interchange format for the Internet. JSON is built on two structures: (1) a collection of name/value pairs and (2) an ordered list of values (http://www.json.org/). Because of this simple approach, JSON is easy to use and it has the potential to be the data interchange format of choice for the Internet. Similar to XML, JSON schemas allow nested structures to model hierarchical data. As data interchange over the Internet increases exponentially due to cloud computing or otherwise, redundancy free JSON data are an attractive form of communication because they improve the quality of data communication through eliminating update anomaly. Nested Normal Form, a normal form for hierarchical data, is a precise characterization of redundancy. A nested table, or a hierarchical schema, is in Nested Normal Form if and only if it is free of redundancy caused by multivalued and functional dependencies. Using Nested Normal Form as a guide, th...

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On Effort and Achievement of Business Undergraduate and Graduate Students under a Disastrous Event

International Education Studies, 2016

The 2011 tornado event in Alabama left college students with a choice to be exempt of their final... more The 2011 tornado event in Alabama left college students with a choice to be exempt of their final examinations or participate in an attempt to improve their overall grades. This incident provided an opportunity to conduct an observational study with the goal of measuring the academic effort of business undergraduate and graduate students. The observation methodology utilized total enrollment of 3804 with an undergraduate enrollment of 3298 and a graduate enrollment of 506 for the spring term of 2011 which included 969 undergraduates and 276 graduates. A stratified random sampling was used to collect enrollment data according to 8 disciplines within the business college. Findings of this study suggest graduate students outperform undergraduate students in grade improvement. In fact, the eligibility rate and successful rate for obtaining a higher grade after taking a final examination for both undergraduates and graduates were statistically insignificant. However, the participation rate for taking the final examination between undergraduates and graduates was statistically different.

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Generating the fewest redundancy-free scheme trees from acyclic conceptual-model hypergraphs in polynomial time

Information Systems, 2014

Generating the fewest redundancy-free scheme trees from conceptual-model hypergraphs is NP-hard [... more Generating the fewest redundancy-free scheme trees from conceptual-model hypergraphs is NP-hard [11]. We show, however, that the problem has a polynomial-time solution if the conceptual-model hypergraph is acyclic. We define conceptual-model hypergraphs, cycles, and scheme trees, and then present a polynomial-time algorithm and show that it generates the fewest redundancy-free scheme trees. As a practical application for the algorithm, we comment on its use for the design of "good" XML schemas for data storage.

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A normal form for precisely characterizing redundancy in nested relations

ACM Transactions on Database Systems, 1996

We give a straightforward definition for redundancy in individual nested relations and define a n... more We give a straightforward definition for redundancy in individual nested relations and define a new normal form that precisely characterizes redundancy for nested relations. We base our definition of redundancy on an arbitrary set of functional and multivalued dependencies, and show that our definition of nested normal form generalizes standard relational normalization theory. In addition, we give a condition that can prevent an unwanted structural anomaly in nested relations, namely, embedded nested relations with at most one tuple. Like other normal forms, our nested normal form can serve as a guide for database design.

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Developing XML documents with guaranteed “good” properties

Abstract. Many XML documents are being produced, but there are no agreed-upon standards formally ... more Abstract. Many XML documents are being produced, but there are no agreed-upon standards formally defining what it means for complying XML documents to have “good ” properties. In this paper we present a formal definition for a proposed canonical normal form for XML doc-uments called XNF. XNF guarantees that complying XML documents have maximally compact connectivity while simultaneously guaranteeing that the data in complying XML documents cannot be redundant. Fur-ther, we present a conceptual-model-based methodology that automat-ically generates XNF-compliant DTDs and prove that the algorithms, which are part of the methodology, produce DTDs to ensure that all complying XML documents satisfy the properties of XNF. 1

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Testing Multi-Factor Models in ADRs: Emerging Market vs. Developed Market

International Journal of Accounting & Finance Review

This paper tests whether the Carhart four-factor model and the Fama-French five-factor model can ... more This paper tests whether the Carhart four-factor model and the Fama-French five-factor model can explain variation in returns of 1,230 ADRs originating from six developed markets and five emerging markets. We aim to compare emerging market ADRs with developed market ADRs in terms of traditional risk factors significance, model fitness and the existence of abnormal returns. Overall, we find that substantial variations exist among ADRs by their origin-of-market. First, both models show that most of the positive abnormal returns we document accrue to emerging market ADRs, mainly Chinese ADRs. Among the risk factors, market risk premium is found to be most prevalent in both emerging and developed markets. Although we find some difference in the presence of particular risk factors employed in the four-factor vs. five-factor model, overall, there are no significant differences in the explanation power between the two models. Lastly, the low R2 values imply that both models do not work ver...

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Introducing Concurrency to Workflows: Theory and A Real-World Case Study

International Journal of Advanced Computer Science and Applications, 2014

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Logical designs of object-relational databases

Irma, 2000

Designing Redundancy-Free XML Schema: A Smallest Closure Approach

International Journal of Cooperative Information Systems, 2015

XML has too many low-level details that hinder high-level conceptual design. We therefore propose... more XML has too many low-level details that hinder high-level conceptual design. We therefore propose DTD graphs and XSD graphs as a mean for conceptual modeling of XML applications. Similar to document type definitions (DTDs) and XML schema definitions (XSDs), DTD graphs and XSD graphs are trees, and as such they can easily be mapped to DTDs and XSDs for implementation. Unlike DTDs and XSDs, DTD graphs and XSD graphs capture various high-level data semantics such as cardinality, ISA, participation, aggregation, categorization, and n-ary relationship. Furthermore, this paper also presents transformation rules between DTDs and a large class of XML Schemas and an algorithm that inputs users’ requirements and outputs a DTD graph that has a minimum number of redundancy-free fragments. As a result of these good properties, the resulting DTD or XSD facilitates query processing and update.

Transforming conceptual models to object-oriented database designs: Practicalities, properties, and peculiarities

Lecture Notes in Computer Science, 1996

More work is needed on devising practical, but theoretically wellfounded procedures for doing obj... more More work is needed on devising practical, but theoretically wellfounded procedures for doing object-oriented database (OODB) &sign. Besides being practical and having formal properties, these design procedures should alSo be flexible enough to allow for peculiarities that make applications unique. In this paper. we present and discuss an OODB design procedure that addresses these problems. The procedure we discuss is practical in the sense that it is based on a common family of conceptual models and in the sense that it does not expect users to supply esoteric, difficult-to-discover, and hard-to-understand constraints (such as multivalued dependencies), nor does it make hard-tocheck and easy-toovchok assumptions (such as the universal relation assumption). At the same time, the pocedure is well-founded and formal, beiig based on a new theoretical result that characterizes properties of interest in designing complex objects. It is also flexible and adaptable to the peculiarities of a wide variety of applications.

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Medical Record Integrated into Nursing Education

Electronic medical record documentation in nursing education National education standards require... more Electronic medical record documentation in nursing education National education standards require that student nurses learn documentation technology Nursing education programs are challenged to implement electronic documentation technology Students have many different levels of technological competency Electronic medical record documentation national requirements United States government electronic records initiatives All medical records will be electronic by 2015

Design Non-recursive and Redundant-Free XML Conceptual Schema with Hypergraph (Extended Abstract)

Lecture Notes in Computer Science, 2011

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