Two metrics in a graph theory modeling of organic chemistry

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 Gª]G', where G,G'∈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 reflected formally many known fundamental chemical rules, in particular, the principle of minimal structural change.