Rule-based Approach

Results will be, depending upon how good the dictionary is. 

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Rule-based Approaches Using Secondary Structure Prediction... 

Ihe rule-based approach to protein structure prediction is obviously very reliant on th quality of the initial secondary structure prediction, which may not be particularly accurate The method tends to work best if it is known to which structural class the protein belongs this can sometimes be deduced from experimental techniques such as circular dichroism... 

The certainty factor approach has been among the more popular rule-based approaches to uncertainty. However, although it is easy to apply given the individual CFs, acquiring the raw CFs from the experts is often quite difficult. Further, although the formulas for CF combination are mathematically appealing, they often have no relation to the ways in which experts combine evidence to arrive at conclusions. Some of the task-specific approaches discussed later address uncertainty combination in a more intuitive way (35). 

Databases and Rule-Based Approaches for Metabolism Prediction... 

DATABASES AND RULE-BASED APPROACHES FOR METABOLISM PREDICTION... 

Kramer, M. A., and Palowitch, B. L., Rule-based approach to fault diagnosis using the signed directed graph, AlChE J. 33(7), 1067-1078 (1987). 

Thus, propanol, C3H70H, has a membership of 1 in the three-carbon molecule class, while ethanol, C2H5OH, has a membership of 0 in the same class. As the membership in a crisp set must take one of only two possible values, Boolean (two-valued) logic can be used to manipulate crisp sets. If all the knowledge that we have can be described by placing objects in sets that are separated by crisp divisions, the sort of rule-based approach to the development of an expert system described in the previous chapter is appropriate. 

BgW The BgVV database has been used to develop specific S AR models for predicting skin irritation and corrosion. These models have been incorporated into a decision support system (DSS). The DSS is mainly a rule based approach, the rules being developed are not only based on substructural features but additionally incorporate specific physicochemical properties such as Log P, molecular weight, and aqueous solubility. The rules have been developed and validated on a total of 1508 compounds of which 199 are classified as hazardous. The DSS is designed to predict EU risk phrases. 

Rule-based approaches are predicated on the analysis of expressions that describe mutations in text the rule set developed is based on patterns that have been analyzed by human experts. Learning of patterns is the basis for machine learning approaches for SNP detection. Similar to the human expert, the machine program makes use of features (attributes) that are used with different frequency and in different combinations when information on mutations is communicated in natural language.21... 

A significant fraction, however, of the documents in the scientific literature dealing with chemical entities and their biological effects are not composed of trivial names for the compounds under investigation. For the automated analysis of the chemical named entities in these publications, we need to use other methods. In principle, it should be possible to use rule-based approaches to identify IUPAC names (and other forms of IUPAC-like expressions), in particular, because the IUPAC name construction itself is based on rules. However, IUPAC names are neither unambiguous, nor can they easily be checked automatically for compliance with IUPAC nomenclature rules. In fact, most IUPAC-like expressions in patent literature seem to be not compliant with the IUPAC nomenclature, and cannot easily be converted into structures.40... 

IUPAC-like expressions, true IUPAC nomenclature names, and InChl and SMILES representations of chemical compounds are well suited for detection by machine learning approaches. Conditional random fields (CRFs)41 and support vector machines have been used for the detection of IUPAC expressions in scientific literature 42 Other approaches are based on rules sets43 44 or combinations of machine learning with rule-based approaches 45 All these approaches have in common that they face one significant problem the name-to-structure problem. 

Recognition of chemical nomenclature names (rule-based approach for the recognition of chemical fragment strings)... 

Recognition of drug names and associated dosage qualifiers (combination of dictionary and rule-based approach for the identification of drug names and the extraction of dosages information)... 

The first is a rule-based system, which makes predictions for untested agents by drawing upon the human interpretation of toxicity data and biological information. That is, it captures, organizes, and applies scientific expertise that relates chemical structures with developmental toxicity. Examples of commercially available rule-based approaches include HazardExpert,23 Deductive Estimation of Risk from Existing Knowledge (DEREK),24... 

Different prediction models have been reported including (i) pharmacophore models that take into account structural features, (ii) linear discriminant models that do not consider structural features, (iii) a modular-binding approach, and (iv) rule-based approaches. The focus of the following discussion is to identify the most important descriptors in the different approaches and relate them to the physicochemical parameters determined in the different P-gp assays. 

A further handicap associated with any rule-based approach to inhibitor design is fhat it tends strongly to lead to just one class of very similar molecules the process often converges to a single (local) minimum. The best approach is Try to extract helpful rules from the available data - but be prepared to break them ... 

In any situation, where no conventional programming approaches exist to solve the problem, rule engines might be an alternative. Here are some typical reasons to decide for a rule-based approach. 

The complexity of the problem would lead to code that is not maintainable in particular, if rules are built in using if-then approaches, the complexity of code may increase dramatically. If code contains more than 20 lines of if-then statements, it is usually a good idea to think about a rule-based approach. 

Peukert et al. (2010a) propose the use of filter operators within match work-flows to prune dissimilar element pairs (whose similarity is below some minimal threshold) from intermediate match results. The threshold is either statically predetermined or dynamically derived from the similarity threshold used in the match workflow to finally select match correspondences. Peukert et al. (2010a) also propose a rule-based approach to rewrite match workflows for improved efficiency, particularly to place filter operators within sequences of matchers. 

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