Table 4.

The costs of relevant edges in the auxiliary graph for computing the value of $G^{\prime }(c,ab)$: note that the cost for the edge (u, v) is exactly value of G(u, v), the size of the maximum common subtree between $T_1(u)$ and $T_2(v)$

G	{cde}	{f}	{g}
{de}	2	0	0
{f}	0	1	0

For computing $G^{\prime }(c,ab)$ we only need the values G between each child of vertex c in $T_1$ (i.e. de and f) and that of vertex ab in $T_2$ (i.e. cde, f, g)