Topological Searching

Berks AH. Cnrrent state of the art of Marknsh topological search systems. World Patent / /2001 23 5-13. 

Berks AH. Current State of the Art of Markush Topological Search Systems. World Patent Inf. 2001 23(19) 5-13. A review of the databases offering topological searching of chemical structures from patents, the indexing, coverage, and searchability of the Markush structures. 

Meyer, E. Topological Search for Classes of Compounds in Large FUes - Even of Markush Formulas - at Reasonable Machine Cost . In Computer Representation and Manipulation of Chemical Information Wipke, W.T. HeUer, S.R. Feldmann, R.J. Hyde, E. Eds. John WUey and Sons New York, 1974 105-122. 

The purpose of adding stereochemistry to Registry connection tables is to make this information available in a form more accessible for computer handling and manipulation. This will permit stereochemical information to be used to enhance structure display and substructure search, both of which currently operate at the topological level. In the case of substructure search, the addition of stereochemical capabilities implies that the user could specify a query with stereochemistry and be given an answer set of structures each of which contains the query with the desired stereochemistry. The incorporation of stereochemical information into substructure search should be, for the most part, a straightforward extension of topological search techniques. However, when that information involves relative, as opposed to absolute, stereochemistry, the search problem can be somewhat more... 

Figure la shows an example of a stereochemical comparison involving absolute and relative stereochemistry. The query substructure and the structure, which is presumed to have been retrieved by a topological search, each have four stereocentres. It is assumed that in the query these stereocentres are grouped into... 

Topological search method derived from mathematic procedures in order to retrieve (and store) chemical substructures, is used e.g, together with the -y GREMAS code. 

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