Article

A Line-Formula Notation System for Markush Structures

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Abstract

A notation system has been developed in the U. S. Patent Office to handle some Markush forms. The system is presented as a supplement to the existing Hayward Notation System which was developed for specific organic chemical structures. The proposed notation system for organic Markush structures is limited to determinate structures of several isolated Markush forms, including those forms that are restricted in substitution depending on the condition of some other Markush group.

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Article
The role of generic structures in the chemical knowledge base is described, with particular reference to patents. Operational information systems providing access to generic structures are reviewed, and past and present research leading to improved services is described.
Article
Categorization, syntax, semantics, and history of generic structural formulas (GSFs) are discussed. Their roles in chemical inference, chemical documentation, and chemistry learning are considered in the context of normalization and formalization of languages of structural formulas, chemical equations, and mechanisms. A formal language (ABSF) of homocomposite GSFs and a heterocomposite language employing normalized structural variables (NVSF) are defined and merged. Useful formal operations involving these languages, their expressive power, and their relationship to Markush SFs and the GENOA and GENSAL languages are considered.
Article
The strategy of an approach to representing and searching the generic chemical formulas (Markush formulas) typical of chemical patents is outlined. The methods under development involve the following stages: (a) the description of generic chemical expressions by means of a formal language, GENSAL; (b) an approach to the generation and recognition of substituents or radicals defined by generic nomenclatural expressions, via formal grammars; (c) methods for automatic generation of screen characteristics, individually and within the relational and logical frameworks defined by generic formulas; (d) search techniques for identification of specific structures and substructures within generic formulas based on these methods.
The history of the development of computer systems for storage and retrieval of Markush structures is reviewed briefly. The systems currently being developed by Chemical Abstracts Service, Derwent Publications/Questel/INPI, and International Documentation Company for Chemistry (IDC) are introduced, and the similarities and differences between the approaches they use for input representation and search are examined, especially in relation to the handling of generic nomenclature, the prospects for future development of such systems is discussed in light of recent and continuing research work, as is the potential for exchange of Markush structure databases between the different search systems.
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