Three different lines of approach have contributed to the theory of
optimal planning. One approach considers the problem from the view-point
of a national government and its adviser, the econometrician planning
speci- alist. The government can, if this is thought to be desirable,
stimulate investment in certain directions and discourage other economic
activities. By various fiscal devices, it can influence both the total
level and the distribution of investment funds over different sectors of
production. Also, in many countries, a public agency plays some kind of
coordinat- ing role in the formulation of long-term plans for output by
the enter- prises sector; this may range from administrative direction
in so-called centrally planned economies, to persuasion and advice in
'capitalist' economies. Accordingly, the public planner wishes to know
what dis- tribution of the nation's resources would be 'optimal'. This
leads to the construction of various models which may be described under
the general heading 'input-output type models'. This type of model has
been largely developed by practitioners, among whom Sandee [B2] is
probably the most outstanding and the earliest. A later, well-developed
example of a model based on this approach is, for example, the Czech
model by Cerny et al. [Bl]. A second approach considers the problem
from the point of view of the private entrepreneur and his adviser, the
manager and financial accountant.