Fuzzy searches

Increasing the fuzziness of object description reduces the number of descriptors used and broadens the scope of a similarity search. At the same time, increasing fuzziness may reduce the discriminatory power of desaiptors to unacceptable levels. Therefore it is desirable to be able to control the degree of fuzziness of desaiptors. 

Asymmetric simhaiity measures allow fuzzy super- and substructure searching. A substructure search is defined as looking for structures containing the given query and a superstructure search is defined as looking for structures embedded in the given query. In both cases asymmetric local similarity is estimated. 

Fuzzy logic and fuzzy set theory are applied to various problems in chemistry. The applications range from component identification and spectral Hbrary search to fuzzy pattern recognition or calibrations of analytical methods. 

Virtual screening on a 2-D basis is far more efficient in terms of computing time, although the information content of the resulting virtual hits is far less sophisticated than for a 3-D pharmacophore search. It is in this setting that combinatorial chemistry approaches are applied most effectively. The many interactions possible with a compound library based on virtual hits compensates for the inherent fuzziness of any prediction tool. Examples have been described where the 2-D structure of a... 

Note that this temporal commitment of the individual to the organization and vice versa is not necessarily some warm and fuzzy joining of hands. The search costs for better jobs or employees are simply too high to recommend more frequent attempts to find better ones. In other words, the initial time commitment comes at the behest of economics, pure and simple. There the matter can stand without going a step further, but in many situations the time breeds trust and mutual reliance, and it is this opportunity that is exploited by high-performance organizations. 

For fuzzy virtual screening purposes, highly active molecules with different scaffolds are combined into an MTree model. By combining the information of remotely related actives into a single model, efficient database searches with molecule ensembles are possible. 

Friedmann El, Ocampo-Friedmann R (1984) The Antarctic crytoendolithic ecosystem relevance to exobiology. Orig Life 14 771-776 Fritsen CH, Priscu JC (1998) Cyanobacterial assemblages in permanent ice covers on Antarctic lakes distribution, growth rate, and temperature response of photosynthesis. J Phytol 34 587-597 Furfaro R et al (12) (2007) The search for life beyond Earth through fuzzy expert systems. Planet Space Sci in press. 

The issue of fuzzification of similarity search has been addressed by Horvath et The first fuzzy similarity metric suggested relies on... 

Similarity Search. A type of "fuzzy" structure searching in which molecules are compared with respect to the degree of overlap they share in terms of topological and/or physicochemical properties. Topological descriptors usually consist of substructure keys or fingerprints, in which case a similarity coefficient like the Tanimoto coefficient is computed. In the case of calculated properties, a simple correlation coefficient may be used. The similarity coefficient used in a similarity search can also be used in various types of cluster analysis to group similar structures. 

To arrive at a conclusion, usually an attempt is made to use absolutely explicit evidence. If such evidence is not available, Eq. (2) may be used to rank the possible conclusions. The best ranked possible conclusion is not necessarily the correct conclusion. Therefore, to reach a reliable conclusion, additional evidence is needed. Fuzzinesss is a description or outcome of the real world, rather than a criterion used in making a decision. The fuzzy degree of a measurement is used to reduce a search space so that the correct answer may be reached more efficiently. For example, from the H NMR spectrum of a peptide, a set of peaks (PS parts per million) is observed as follows ... 

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