The synthesis of imperative programs for hierarchical, algebraically specified abstract data types is investigated. Two aspects of the synthesis are considered: the choice of data structures for efficient implementation, and the synthesis of linked implementations for the class of ADTs which insert and access data without explicit key. The methodology is based on an analysis of the algebraic semantics of the ADT. Operators are partitioned according to the behaviour of their corresponding operations in the initial algebra. A family of relations, the storage relations of an ADT, Is defined. They depend only on the operator partition and reflect an observational view of the ADT. The storage relations are extended to storage graphs: directed graphs with a subset of nodes designated for efficient access. The data structures in our imperative language are chosen according to properties of the storage relations and storage graphs. Linked implementations are synthesised in a stepwise manner by implementing the given ADT first by its storage graphs, and then by linked data structures in the imperative language. Some circumstances under which the resulting programs have constant time complexity are discussed.

The prevalence of graph-structured data in modern real-world applications has led to a rejuvenation of research on graph data management and analytics. Several database query languages have been proposed for textually querying graph databases. Unfortunately, formulating a graph query using any of these query languages often demands considerable cognitive effort and requires "programming" skill at least similar to programming in SQL. Yet, in a wide spectrum of graph applications consumers need to query graph data but are not proficient query writers. Hence, it is important to devise intuitive techniques that can alleviate the burden of query formulation and thus increase the usability of graph databases. In this dissertation, we take the first step to study the graph query autocompletion problem. We provide techniques that take a user's graph query as input and generate top-k query suggestions as output, to help to alleviate the verbose and error-prone graph query formulation process in a visual environment. Firstly, we study visual query autocompletion for graph databases. Techniques for query autocompletion have been proposed for web search and XML search. However, a corresponding capability for graph query engine is in its infancy. We propose a novel framework for graph query autocompletion (called AutoG). The novelties of AutoG are as follows: First, we formalize query composition that specifies how query suggestions are formed. Second, we propose to increment a query with the logical units called c-prime features, that are (i) frequent subgraphs and (ii) constructed from smaller c-prime features in no more than c ways. Third, we propose algorithms to rank candidate suggestions. Fourth, we propose a novel index called feature DAG (FDAG) to further optimize the ranking. Secondly, we propose user focus-based graph query autocompletion. AutoG provides suggestions that are formed by adding subgraph increments to arbitrary places of an existing user query. However, humans can only interact with a small number of recent software artifacts in hand. Hence, many such suggestions could be irrelevant. We present the GFocus framework that exploits a novel notion of user focus of graph query formulation. Intuitively, the focus is the subgraph that a user is working on. We formulate locality principles to automatically identify and maintain the focus. We propose novel monotone submodular ranking functions for generating popular and comprehensive query suggestions only at the focus. We propose efficient algorithms and an index for ranking the suggestions. Thirdly, we propose graph query autocompletion for large graphs. Graph features that have been exploited in AutoG are either absent or rare in large graphs. To address this, we present Flexible graph query autocompletion for LArge Graphs, called FLAG. We propose wildcard label for query graph and query suggestions. In particular, FLAG allows augmenting users' queries using subgraph increments with wildcard labels, which summarize query suggestions that have similar increment structures but different labels. We propose an efficient ranking algorithm and a novel index, called Suggestion Summarization DAG (SSDAG), to optimize the online suggestion ranking. Detailed problem analysis and extensive experimental studies consistently demonstrate the effectiveness and robustness of our proposed techniques in a broad range of settings.

Thesis (M.B.A.)--Boston University

This thesis deals with the topic of programming linguistics. A survey of the current techniques in the fields of syntax analysis and semantic synthesis is given. An extensible automatic translator has been described which can be used for the automatic translation of a class of programming languages. The automatic translator consists of two major parts: the syntax analyser and the semantic synthesizer. The syntax analyser is a generalised version of LL(K) parsers, the theoretical study of which has already been published by Lewis and Stearns and also by Rosenkrantz and Stearns. It accepts grammar of a given language in a modified version of the Backus Normal Form (MBNF) and parses the source language statements in a top down, left to right process without ever backing up. The semantic synthesizer is a table driven system which is called by the parser and performs semantic synthesis as .the parsing proceeds. The semantics of a programming language is specified in the form of semantic productions. These are used by the translator to construct semantic tables. The system is implemented in SN0B0L4 (SPITBOL version 2.0) on an IBM 360/44 and its description is supported by various examples. The automatic translator is an extensible system and SN0B0L4, the implementation language appears as its subset. It can be used to introduce look ahead in the parser, so that backup can be avoided. It can also be used to introduce new facilities in the semantic synthesizer.

The thesis describes a method of translating the computer language APL to other high-level languages. Particular reference is made to FORTRAN, a language widely available to computer users. Although gaining in popularity, APL is not at present so readily available, and the main aim of the translation process is to enable the more desirable features of APL to be at the disposal of a far greater number of users. The translation process should also speed up the running of routines, since compilation in general leads to greater efficiency than interpretive techniques. Some inefficiencies of the APL language have been removed by the translation process. The above reasons for translating APL to other high-level languages are discussed in the introduction to the thesis. A description of the method of translation forms the main part of the thesis. The APL input code is first lexically scanned, a process whereby the subsequent phases are greatly simplified. An intermediate code form is produced in which bracketing is used to group operators and operands together, and to assign priorities to operators such that sub-expressions will be handled in the correct order. By scanning the intermediate code form, information is stacked until required later. The information is used to make possible a process of macro expansion. Each of the above processes is discussed in the main text of the thesis. The format of all information which can or must be supplied at translation time is clearly outlined in the text.

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M.Com. (Computer Auditing) / In this chapter the actual topic will be presented. The reason for this study will be motivated with reference to current audit developments. This chapter will also highlight the constraints of the study. This is necessary to clearly identify the application of this essay in practice. The reader of this essay should be able to identify the relevance and possible applications of this study after having read chapter 1. In the past few years substantial attention has been given to auditing aspects of system software. The way system software operates and interacts, and the impact on the auditability of computer based systems were issues discussed in the EDP auditing environment. Auditors are now concentrating on using technology to assist in the performance of their audit procedures. The reasons for this are multiple, but for the purposes of this document only the major reasons will be highlighted.

Submitted in partial fulfilment of the academic requirements for the Degree of Doctoral of Technology in Mechanical Engineering, Durban Institute of Technology, 2005. / Increased global competition is challenging manufacturing industries to bring competitively priced, well-designed and well-manufactured products into the marketplace as quickly as possible. Manufacturing companies are responding to these challenges in their industry by extending current internet trends to create virtual marketplaces where factories, suppliers, and customers are part of the solution. Pressing demands to reduce lead-time by providing a suitable manufacturing price for a product has become an important step in the current competition age. This thesis presents an approach for providing a quotation for a product via the web, automatically and autonomously. / D

M.Com. (Computer Auditing) / Please refer to full text to view abstract