Backward Searching

A computer-assisted process for solving problems. Setting out from a target, a path to potential starting points is searched in a backward direction. This method is used for computer-assisted synthesis planning to find suitable synthesis precursors or available starting materials. 

The increase in the total energy of a supersystem (the system formed by noncovalent interaction between two or more molecular entities, e.g., a hydrogen bonded system) resulting from too small a basis set describing the supersystem and subsystems differently. The BSSE is an artificial mathematical effect causing an overestimation of the interaction energy. 

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Techniques for the synthesis of reaction paths on the basis of enumeration of all possible reactions are fairly weU developed. The SYNCHEM2 system conducts a backward search of possible reaction paths from a desired product (76). Because the procedure is limited by the rapid growth of... 

These rules are used to reason backward that is, MYCIN starts with a hypothesis that needs to be validated and then works backward, searching the rules in the rule base that match the hypothesis. The hypothesis can be either verified with a certainty factor or can be proven wrong. 

The dependency of the auditory reaction times from the type of the last target stimuli could give important hints to some kind of backward search. The other possibility is that the scanning mechanism uses the whole set of target stimuli and keys without making a difference. Some considerations will be given in the next section. 

BFS is based on sequential backward search (SBS) and sequential forward search (SFS), of which SBS eliminates the least important feature one by one, while SFS adds the most important feature one by one. The least important feature means that for a subset, there exists RerriSv>-fx)important feature means that for a subset which satisfies and S ri5 =0, there... 

As regards of correctness, the PDG-based and the SLV-based slicing compute the same slices in all our experiments. Otherwise the experiments compare running times and memory consumption, and we compute speedup figures. The parsing time is not included in the running times for any method. For CodeSurfer, which also performs a number of other analyses, the time is measured as the time to build the PDG plus the time to perform the backwards search to form the slice. The resolution of the time reported by CodeSurfer to build the PDG is whole seconds, which limits the precision of the computed execution time. In some experiments the reported time for building the PDG is zero those cases are marked as in the tables. 

In backward chaining, the inference engine would search through the knowledge base until it found a rule, the conclusion of which was "Go to live with mother." It would find three such rules ... 

Gavetti, G. Levinthal, D. 2000. Looking forward and looking backward cognitive and experiential search. Administrative Science Quarterly, 45 113-137. 

This function is used to find V0l and is similar to the Voh function. Note that Vol is also defined where the slope of the transfer curve is -1. To distinguish V0h and V0l. this function finds the point starting from the end of the trace and searching backwards. There are two points on the trace where the slope is -1. This function finds the point closest to the end of the trace. 

In searching for mechanisms involving excited oxygen atoms have you discovered any processes involving the vibrationally excited states of either the ground electronic state or low-lying excited states of O2 which would drive these chemical cycles backward Have you considered candidate reactions other than those already identified for the production of odd oxygen in the stratosphere ... 

The Corey-Wipke approach considered above actually represents a backward computer-assisted search of synthetic pathways, which is set up as an interactive procedure with the operator helping to guide the selection of the most promising routes. In this approach the computer is assigned to the job of accumulation, storage, and processing of all chemical information amenable to formalization, while the chemist is supposed to make a final evaluation of the suggested retrosynthetic solutions and to control the direction of further searches. 

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