The nature of the generic chemical structures found in patents is described, with a discussion of the types of statement commonly found in them. The available representations for such structures are reviewed, with particular note being given to the suitability of the representation for searching files of such structures. Requirements for the unambiguous representation of generic structures in an "ideal" storage and retrieval system are discussed. The basic principles of the theory of formal languages are reviewed, with particular consideration being given to parsing methods for context-free languages. The Grammar and parsing of computer programming languages, as an example of artificial formal languages, is discussed. Applications of formal language theory to chemistry and information work are briefly reviewed. GENSAL, a formal language for the unambiguous description of generic structures from patents, is presented. It is designed to be intelligible to a chemist or patent agent, yet sufficiently ABSTRACT formaLised to be amenabLe to computer anaLysis. DetaiLed description is given of the facilities it provides for generic structure representation, and there is discussion of its Limitations and the principLes behind its design. A connection-tabLe-based internaL representation for generic structures, caLLed an ECTR (Extended Connection Table Representation) is presented. It is designed to represent generic structures unambiguousLy, and to be generated automatically from structures encoded in GENSAL. It is compared to other proposed representations, and its implementation using data types of the programming Language PascaL described. An interpreter program which generates an ECTR from structures encoded in a subset of the GENSAL Language is presented. The principles of its operation are described. Possible applications of GENSAL outside the area of patent documentation are discussed, and suggestions made for further work on the development of a generic structure storage and retrieval system based on GENSAL and ECTRs.

In an age where information has become a crucial commodity, accessing appropriate information quickly is essential to economic success. Developing ways of improving information retrieval is therefore of central concern to human factors and technologists alike. One aspect of information access relates to the ability of individual office workers to manage and retrieve their own information effectively, and this is what the present research addresses. Previous work in the area has been dominated by designing computer interfaces for the average user. This research investigates how people's needs might differ according to circumstance and examines a wider range of design possibilities. Specifically it sets out to relate retrieval problems (specific information retrieval rather than e.g. browsing or reminding) to job and individual (personality) differences within the general context of personal information management in offices using traditional technologies of paper, filing cabinets and desks. This is achieved by both extensive fieldwork and the use of simulated filing-retrieval systems in a controlled context.

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Distribution design for databases usually addresses the problems of fragmentation, allocation and replication. However, the main purposes of distribution are to improve performance and to increase system reliability. The former aspect is particularly relevant in cases where the desire to distribute data originates from the distributed nature of an organization with many data needs only arising locally, i.e., some data are retrieved and processed at only one or at most very few locations. Therefore, query optimization should be treated as an intrinsic part of distribution design. Due to the interdependencies between fragmentation, allocation and distributed query optimization it is not efficient to study each of the problems in isolation to get overall optimal distribution design. However, the combined problem of fragmentation, allocation and distributed query optimization is NP-hard, and thus requires heuristics to generate efficient solutions. In this thesis the foundations of fragmentation and allocation in databases on query processing are investigated using a query cost model. The considered databases are defined on complex value data models, which capture complex value, object-oriented and XML-based databases. The emphasis on complex value databases enables a large variety of schema fragmentation, while at the same time it imposes restrictions on the way schemata can be fragmented. It is shown that the allocation of locations to the nodes of an optimized query tree is only marginally affected by the allocation of fragments. This implies that optimization of query processing and optimization of fragment allocation are largely orthogonal to each other, leading to several scenarios for fragment allocation. Therefore, it is reasonable to assume that optimized queries are given with subqueries having selection and projection operations applied to leaves. With this assumption some heuristic procedures can be developed to find an “optimal” fragmentation and allocation. In particular, cost-based algorithms for primary horizontal and derived horizontal fragmentation, vertical fragmentation are presented.