Instance classification

Instance classification deduces a type (class) for an instance. In the ontology above, we declared the domain mo Engine and the range mo Supplier for the mo hasSupplier property. If the mo hasSupplier relation holds between instances mo Ela and mo Sla, then an inference engine will automatically deduce that the type of mo Ela is mo Engine (since the mo hasSupplier property has its domain restricted to instances from this class) while mo Sla is of type mo Supplier (since the mo hasSupplier property has its range restricted to instances from this class). Therefore, an instance classification was performed. 

It will be convenient to discuss instances of interrelations between vitamins under separate headings according to the circumstances under which they have been observed. Clearly, however, such classification will often depend on the particular aspect of the complete story which has so far come to light. An interrelation which has already been found in vwo may later be found in vUro, or vice versa, as indeed has already occurred in one instance. Classification is therefore based on the evidence at present available, and the distinctions drawn between different types of interrelation may not always be genuine. 

To recognize reaction classification as an important step in learning from reaction instances... 

Since 1970 a variety of reaction classification schemes have been developed to allow a more systematic processing of the huge variety of chemical reaction instances (see Chapter III, Section 1 in the Handbook). Reaction classification serves to combine several reaction instances into one reaction type. In this way, the vast number of observed chemical reactions is reduced to a manageable number of reaction types. Apphcation to specific starting materials of the bond and electron changes inherent in such a reaction type then generates a specific reaction instance. 

HORACE used alternating phases of classification (which topological or physicochemical features are required for a reaction type) and generalization (which features are allowed and can be eliminated) to produce a hierarchical classification of a set of reaction instances. 

Reaction types can be derived automatically through classification of reaction instances. 

By applying the BROAD classification feature to the hit list of the first example, described in Section 5.13.2, 18 clusters arc found, llic second reaction instance of the first cluster is shown in figure 5-30. 

Figure 5-30. Second reaction instance of the first cluster for Example 1, obtained by applying the BROAD classification method,...

Classification describes the process of assigning an instance or property to one of several given classes. The classes are defined beforehand and this class assignment is used in the learning process, which is therefore supervised. Statistical methods and decision trees (cf. Section 9.3) are also widely used for classification tasks. 

Decision trees give a graphical representation of a procedure for classification. They consist of nodes and branches the leaf nodes give the classification of an instance. 

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. 

Kinds of Catalyzed Organic Reactions A fundamental classification of organic reactions is possible on the basis of the lands of bonds that are formed or destroyed and the natures of eliminations, substitutions, and additions of groups. Here a more pragmatic hst of 20 commercially important lands or classes of reactions will be discussed. In all instances of sohd-catalyzed reactions, chemisorption is a primary step. Often molecules are dissociated on chemisorption into... 

In molecules with little or no symmetry, it may still be possible to recognize the main localized-orbital component of certain molecular orbitals. It is then convenient to adopt the label of this localized type as the label of the molecular orbital, even though the molecular symmetry does not coincide with the local symmetry. For instance, in methylenimine again, the 5A orbital is clearly built out of the in-plane 7rc 2 group orbital, with a small NH component. We therefore label the orbital t CU2, although the molecule does not have a vertical symmetry plane. Similarly, the orbitals 7A and 8A of propylene are labeled 7TqH3, tt CU2 (111.49).a Other examples where the local symmetry is sufficiently preserved and only weakly perturbed by the molecular environment are hydrazine (111.34) and methylamine (III.31). In some cases we have omitted the label as no unambiguous classification is possible. 

Cadherins are a superfamily of Ca2+-sensitive cell-cell adhesion molecules, which cause homophilic cell interactions. Cadherins can be divided into different subfamilies, namely, classical cadherins, desmosomal cadherins, protocadherins, and nonconventional cadherins (7TM cadherins, T-cadherin, FAT). Classical cadherins are often denoted by a prefix reflecting their principal expression domains e.g., E is epithelial, N is neuronal, and P is placental. However, this classification is not stringent, as for instance E-cadherin can also be found in certain neuronal tissues, and N-cadherin is also found in epithelial cells. Among the desmosomal cadherins, two subfamilies can be distinguished the desmocollins 1-3 and the desmogleins 1-4. 

There have been few satisfactory demonstrations that decompositions of hydrides, carbides and nitrides proceed by interface reactions, i.e. either nucleation and growth or contracting volume mechanisms. Kinetic studies have not usually been supplemented by microscopic observations and this approach is not easily applied to carbides, where the product is not volatile. The existence of a sigmoid a—time relation is not, by itself, a proof of the occurrence of a nucleation and growth process since an initial slow, or very slow, process may represent the generation of an active surface, e.g. poison removal, or the production of an equilibrium concentration of adsorbed intermediate. The reactions included below are, therefore, tentative classifications based on kinetic indications of interface-type processes, though in most instances this mechanistic interpretation would benefit from more direct experimental support. 

Inevitably, there is a certain degree of overlapping between these two general classifications. For instance, CVD optical applications are found as both coatings and fibers while fibers are used in optics as well as in structural and mechanical applications. These relationships will be reviewed in the several chapters on applications. 

The chemical and physical properties of the polymers obtained by these alternate methods are identical, except insofar as they are affected by differences in molecular weight. In order to avoid the confusion which would result if classification of the products were to be based on the method of synthesis actually employed in each case, it has been proposed that the substance be referred to as a condensation polymer in such instances, irrespective of whether a condensation or an addition polymerization process was used in its preparation. The cyclic compound is after all a condensation product of one or more bifunctional compounds, and in this sense the linear polymer obtained from the cyclic intermediate can be regarded as the polymeric derivative of the bifunctional monomer(s). Furthermore, each of the polymers listed in Table III may be degraded to bifunctional monomers differing in composition from the structural unit, although such degradation of polyethylene oxide and the polythioether may be difficult. Apart from the demands of any particular definition, it is clearly desirable to include all of these substances among the condensation... 

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