Topological torsion fragment

Figure 4 Example atom pair and topological torsion fragments. The information included in the circled atom environments is given below the fragment-type label.

A wide variety of features have been used in bit vectors, including molecular fragments, 3-D potential pharmacophores, atom pairs, 2-D pharmacophores, topological torsions, and variety of topological indices. 

A tremendous number of various fragments are used in structure-property studies atoms, bonds, topological torsions , chains, cycles, atom- and bond-centered fragments, maximum common substructures, line notation (WLN and SMILES) fragments, atom pairs and topological multiplets, substituents and molecular frameworks, basic subgraphs, etc. Their detailed description is given below. 

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