More on the line graph model for predicting physico-chemical properties ofalkanes

The iterated line graph sequence Li, i=1,2,..., of a graph G is defined so that L-1 is the line graph of G, L-2 is the line graph of L-1, etc. Let G b e a molecular graph possessing mo edges and let mi be the number of edges o f L-i, i=1,2,.... We examine the applicability of the linear model a(0)m(i0 )+a(1)m(i1) + +a(2)m(i2) +... +a(k)m(ik)+ b for predicting physico-chemical properties of alkanes (boiling points, molar volumes, molar refractions, h eats of vaporization, critical temperatures, critical pressures and surface tensions). For all properties studied, the optimal model has k=2, i(0)=0, i(1)=1, but i(2) varies between 2 and 4.