Algorithm for computer perception of topological symmetry

For the exhaustive and irredundant generation of candidate structures in ESESOC (Expert System for the Elucidation of the Structures of Organic Compounds), a new algorithm for computer perception of topological equivalence classes of the nodes (non-hydrogen atoms) in molecular graphs or partial structures was developed. Two new matrices, node matrix (N) and bond matrix (B), are devised. A new graph invariant, the weight of the node, is suggested for characterizing the symmetry.