Needless to say, over the years DP scholars expanded the scope of operation
of DP and developed numerous abstract axiomatic formulations of DP (e.g. Ellis,
1955; Brown and Strauch, 1965; Verdu and Poor, 1987; Bird and de Moor, 1997).
It is precisely for this reason that it is important to stress that Bellman’s
advice is as valid today as it was in 1957.