Global similarity

A theoretical foundation of molecular similarity analysis is the assumption of neighborhood behavior ,which refers to the tendency of molecules with globally similar structures to exhibit similar biological activity. The well-known similarity-property principle (SPP) of Johnson and Maggiora expresses this paradigm and promotes a holistic view of molecular structure and properties. Molecular similarity applications assume that chemical similarity can be related to biological activity in a meaningful manner. However, the success of this approach ultimately depends on the way molecular similarity is defined. 

Each member in an ensemble uses a local aggregation function (such as average) to generate a schema matching similarity measure from the similarity measures of the attribute correspondences. Local similarity measures can then be aggregated using a global similarity measure (e.g., max) to become the ensemble similarity... 

Note that the threshold may be a parameter applied to a global similarity value, i.e., different similarity values are aggregated into a global one (given a strategy, see Sect. 5) and the threshold represents the decision-maker for accepting the pair of schema elements as a correspondence or not. 

Often, the shape comparisons of local regions of molecules are of interest, which, in many instances, may appear more important than the evaluation of the global similarities of molecules. 

Thus, in this case, global similarity-based LEVS methods successfully identified a new inhibitory chemotype that would not have been found had the known pharmacophore constraints taken into account. 

Depending on the objective of the study, free sorting may be performed considering one or several sensory modalities and the criterion for grouping the objects may be specified (texture, odor, etc.). In contrast, if the global similarity between stimuli is of interest, the subjects are advised that they are free to use any characteristic of the products to form coherent and homogeneous groups. 

The consumers used from 3 to 11 attributes to describe the 12 perfumes. The number of attributes used by the experts and by the consumers was globally similar but experts used on average slightly more terms than consumers (7.8 terms compared to... 

The similarity between the target case and all the source cases is calculated using nearest neighbor method. The evaluation of the global similarity between the target and a source case is based on the computation of the local similarities. The local similarity deals with a single attribute, and takes the value from the interval [0 1]. Thus, from the local similarities the global similarity can be derived as ... 

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