Topological algorithms, structural effects

From topological algorithms . This method is best restricted to steric effects and polarizability parameters. The nature of topological parameters has been described. They are composite parameters and result from a count of structural features. ... 

In both directions of the solution-seeking process (from the structure as input toward the spectrum, or vice versa) the system first transforms the input data into the representations it understands, i.e., the representations that enable the algorithms to be performed. The most standard spectral data are the peak positions, intensities, and shapes of the specific parts of the spectral curve, the area below the curves and the periodic patterns of peaks in the spectra. The main structural features are the spatial and topological relations of structural fragments with the aspect to the rest of the structure. Topological properties are deduced from connection tables, while spatial positions, orientations, and possible degrees of freedom of rotation or vibration of structural parts are usually obtained in an interactive online dialog with the user. However, the system must be able to detect the positions in a structure where certain spatial effects may occur and ask the user for detailed instructions if the questions cannot be resolved due to lack of data. 

Besides choosing an appropriate representation, its layout must be correct if it is to be readable, revealing the network s overall structure and important features. Layout algorithms compute positions for each vertex from the graph topology, sometimes augmented with a (dis)similarity function between vertices. For NL, a position is a 2D or 3D point for MAT, a ID ordering. Some layout methods are specific for one representation, while others can be applied to both. We review those considered most effective for social network visualizations. 

---