Interpretation:
Control switches to u*=*=0 at . i.e, it requires at
least units of time to retain a dollar of earnings to
be worthwhile. That means, it pays to invest as much
earnings as feasible before and it does not pay
to invest any earnings after .Thus, is the
point of indifference between retaining earnings or
paying dividends out of earnings.
Suppose the firm invests one dollar of earnings at .
Since this is the last time any earnings invested will
pay off, it is obvious that this dollar will yield dividends
at the rate r from to T. (i.e, under the optimal
policy)