The problem of an optimum temperature sequence in stirred tank reactors was proposed by Denbigh and then discussed from the dynamic programming point of view by Aris, is here reconsidered by means of the discrete maximum principle.
The general method is given to deal with Denbigh's problems for any numerical examples by means of this principles. For the same numerical example as Aris', the solutions, not only for the case without the physical restrictions imposed on temperature and holding times, but also for the case with them, are given for single reactor, two reactor and three reactor system, compared with Aris’solutions.
The solutions are solved analytically for single reactor and two reactor system.
The comment on Aris’paper for the policies under the restrictions is given.