Two different metrics in the graph theory model of organic chemistry are defined. The chemical distance between two graphs (molecules) taken from the same family of isomeric graphs Fpq (where p is a number of vertices and q is a number of edges and loops) is based on the maximal common subgraph. The reaction distance assigned to a transformation G ⇒ G′, where G, G′ ε Fpq, is equal to the minimal number of the so-called elementary transformations that are necessary for the transformation of G onto G′. Both the suggested metrics reflect formally many known fundamental chemical rules, in particular, the principle of minimal structural change. © 1992.
Baláž, V., Kvasnička, V., & Pospíchal, J. (1992). Two metrics in a graph theory modeling of organic chemistry. Discrete Applied Mathematics, 35(1), 1–19. https://doi.org/10.1016/0166-218X(92)90292-I