Substructure isomorphism matrix

A substructure isomorphism matrix n x p contains binary elements describing which of the given p query structures (substructures) are part of the give n n target structures (molecular structures). Such a matrix can be used to investigate the diversity of the target structures and allows the character ization and comparison of structural libraries. A quadratic substructure is omorphism matrix n x n is obtained if the same structures are used as molec ular structures and as substructures; this matrix contains full information about the topological hierarchy of the n structures. A hierarchical arrang ement of chemical structures is useful for the evaluation of results obtain ed from searches in structure databases.