Structure graphs indexing

In addition to fragment and graph indexing of polymer information, the POLID-CAS YR system also makes use of two distinct vocabularies for non-structural terms. The first vocabulary is, in essence, a controlled vocabulary of hierarchically ordered terms (taxonomy), supplemented by a second, more fluid vocabulary, which is subject to constant editing. The latter is used to further enhance the controlled vocabulary, e.g., the term isomerization , which is part of the controlled vocabulary, could be defined further by the terms racemization , tautomerization or rotation isomerization . Annotation of this kind is only a short step away from techniques, which we now associate with the terms tagging and folksonomies and which are typical components of Web 2.0 systems. POLIDCASYR s controlled vocabulary is structured according to a number of semantic categories such... 

Information may be stored in the architecture of the receptor, in its binding sites and in the ligand layer surrounding bound <7 it is read out at the rate of formation and dissociation of the supermolecule. In addition to size and shape, a receptor is characterized by the dimensionality, the connectivity and the cyclic order of its structural graph these features have been used to define a ligand structural index L ... 

These are global molecular descriptors derived from an H-depleted molecular graph where each vertex is weighted by a local vertex invariant called Atom-in-Structure Invariant Index (ASII) defined as [Bangov, 1988] ... 

Chemical graph theory has been the basis for new applications in structure-property methods during recent years. With an emphasis on the molecular skeleton, numerical indexes have been developed that represent features of molecular structure. These indexes are numerical values that parallel variation... 

In the case of k, the structures and index values in Table 3 for A = 7 reveal that information is encoded relating to the degree of star graph-likeness and... 

Figure 6-1. Different forms of representation of a chemical graph a) labeled (numbered) graph b) adjacency matrix c) connectivity table, type I d) connectivity table, type II f) line notations g) structural index.

Molecular Connectivity Indexes and Graph Theory. Perhaps the chief obstacle to developing a general theory for quantification of physical properties is not so much in the understanding of the underlying physical laws, but rather the inability to solve the requisite equations. The plethora of assumptions and simplifications in the statistical mechanics and group contribution sections of this article provide examples of this. Computational procedures are simplified when the number of parameters used to describe the salient features of a problem is reduced. Because many properties of molecules correlate well with structures, parameters have been developed which grossly quantify molecular structural characteristics. These parameters, or connectivity indexes, are usually based on the numbers and orientations of atoms and bonds in the molecule. 

The article reports investigations of the topological properties of benzenoid molecules which the author has performed in the last 20 years. Emphasis is given on recent developments and other scientists contributions to these researches. Topics covered in recent books and reviews are avoided. The article outlines spectral properties, some aspects of the study of Kekule and Clar structures, the Wiener index as well as a number of graphs derived from benzenoid systems (inner dual, excised internal structure, Clar graph, Gutman tree, coral and its dual). 

---