** Solving Equations for Derived Graph**

For the head node of an interval of the derived graph, compute:

* X _{b}^{M} = &prod_{i &isin &Gamma^-1 b} Y_{b}^{M} *

Then, for each node * c * in the interval, update its output vector:

* Y _{c}^{M} = X_{b}^{M} · Y_{c}^{M} +
X_b^{M} * · Y_c^m

As this process is continued through levels of the derived graph,
eventually it terminates because the top level is a single node
whose inputs * X _{e}^{M} = 0 * are known because it is the entry block.

The algorithm can be viewed as updating the minimal and maximal available vectors until they become the same. By using the derived graphs, the updating is done efficiently.