Strategy search

Besides structure and substructure searches, Gmclin provides a special search strategy for coordiuation compouuds which is found in no other database the ligand search system, This superior search method gives access to coordination compounds from a completely different point of view it is possible to retrieve all coordination compounds with the same ligand environment, independently of the central atom or the empirical formula of the compound. 

One of the most important questions for a conformational search strategy is, When have I found all of the energetically interesting con formers This is an area of active research and the ideal answer seems to be, When you find all of the local minima. However, this answer is not always reasonable, because medium to large molecules have a large number of minima (see Complexity of Potential Energy Surfaces on page 14). 

Subject-Based Retrieval Parameters. There are numerous means by which the subject content of a patent can be expressed, and which a searcher can use in developing a search strategy. Different databases offer differing subsets of these means. Effective strategies should in general not be limited to a single type of retrieval parameter rather, they should be built from different parameters and modified as needed to provide the strategy best fitted to the subject at hand. 

Patent classification codes are another subject-search parameter available in most patent databases. IPC codes are usually present and U.S. codes exist in a number of files in the case of Japan Patent Information Organization (JAPIO), Japanese codes too are available. It is possible to mimic a hand search by limiting operations to references falling within one class or group of classes. Although such strategies can in some instances be justified, it is usually wiser to treat class codes as just one of the various subject parameters that make up a search strategy. 

Databases differ in their strengths and weaknesses, as well as in their focus. As a result, dupHcate searches carried out on different databases generally produce different results. This has been demonstrated in comparative studies of retrieval results for a group of patent databases (31,32). Participants in one study (31) made an effort to develop optimal search strategies in each database tested, yet in no instance did one file produce perfect retrieval. Both investigations (31,32) found that results from the various databases complemented each other. As a result, searchers are counseled to use multiple databases whenever possible. There is no pat answer to the question of how many files to use or which files to use however, more files mean more expenditure, and searchers must develop their own cost—benefit relationship. 

Once the objective and the constraints have been set, a mathematical model of the process can be subjected to a search strategy to find the optimum. Simple calculus is adequate for some problems, or Lagrange multipliers can be used for constrained extrema. When a Rill plant simulation can be made, various alternatives can be put through the computer. Such an operation is called jlowsheeting. A chapter is devoted to this topic by Edgar and Himmelblau Optimization of Chemical Processes, McGraw-HiU, 1988) where they list a number of commercially available software packages for this purpose, one of the first of which was Flowtran. 

M Vieth, ID Hirst, BN Dominy, H Daigler, CL Brooks III. Assessing search strategies for flexible docking. J Comput Chem 19 1623-1631, 1998. 

The success of any method using this fonnalism will be entirely dependent on the function/used and the search strategy. Lathrop et al. [19] use a branch-and-bound algo-... 

In addition to evolutionary search strategies such as GAs, there are a number of other search techniques that are employed for design optimization. 

This brute-force search strategy is followed as more layers are added because we do not know how many layers we need for the prescribed load. If the load is very high, perhaps we will need 19 layers, and we will work our way up to that laminate by adding one layer at a time and finding the best laminate of that number of laminae. 

The simplest procedure is merely to assume reasonable values for A and to make plots according to Eq. (2-52). That value of A yielding the best straight line is taken as the correct value. (Notice how essential it is that the reaction be accurately first-order for this method to be reliable.) Williams and Taylor have shown that the standard deviation about the line shows a sharp minimum at the correct A . Holt and Norris describe an efficient search strategy in this procedure, using as their criterion minimization of the weighted sum of squares of residuals. (Least-squares regression is treated later in this section.)... 

Ewing TJ, Makino S, Skillman AG, Kuntz ID. DOCK 4.0 search strategies for automated molecular docking of flexible molecule databases. J Comput Aided Mol Dei 2001 15 411-28. 

The molecular modelling approach, taking into account the pyruvate—cinchona alkaloid interaction and the steric constraints imposed by the adsorption on the platinum surface, leads to a reasonable explanation for the enantio-differentiation of this system. Although the prediction of the complex formed between the methyl pyruvate and the cinchona modifiers have been made for an ideal case (solvent effects and a quantum description of the interaction with the platinum surface atoms were not considered), this approach proved to be very helpful in the search of new modifiers. The search strategy, which included a systematic reduction of the cinchona alkaloid structure to the essential functional parts and validation of the steric constraints imposed to the interaction complex between modifier and methyl pyruvate by means of molecular modelling, indicated that simple chiral aminoalcohols should be promising substitutes for cinchona alkaloid modifiers. Using the Sharpless symmetric dihydroxylation as a key step, a series of enantiomerically pure 2-hydroxy-2-aryl-ethylamines... 

It is already clear from this small example that aspects such as conflict resolution can have an important influence on the performance of the search strategy. 

In this case, the breadth first search yields the optimum with a fewer number of nodes to be searched. Different search strategies than the ones used here can readily be used10. It is likely that different problems would be suited to different search strategies. 

Various search strategies can be used to locate the optimum. Indirect search strategies do not use information on gradients, whereas direct search strategies require this information. These methods always seek to improve the objective function in each step in a search. On the other hand, stochastic search methods, such as simulated annealing and genetic algorithms, allow some deterioration... 

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