An algorithm, MOLORD, is proposed for defining real number invariants
for subgraphs of various sizes in molecular graphs. The algorithm is b
ased on iterative line derivatives and accounts for heteroatoms by mea
ns of their electronegativities. It can be used in topological equival
ence perception as well as to provide local and global descriptors for
QSPR or OSAR studies. The algorithm is implemented on a TURBO PASCAL,
TOPIND program and examplified on a set of selected graphs.