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regions. This means that each project can be presented in 
R? alternative versions. With the aid of our model we can 
determine the additional incomes it creates in the R regions 
and hence also the weighted sum of regional incomes represent- 
ing the increase in welfare. We can also determine the total 
capital to be invested in the bunch of projects consisting of the 
investment of one million in the international sector plus the 
investments in the regional and national sectors. The method 
to be used is that we put equal to zero the investment in all 
other international sectors. I have proposed to speak of the 
semi-input-output method [1]. Thus the income-capital ratio 
for all R? versions of the project can be found. The version 
with the highest ratio is the « best version ». We may now 
make a list of the ratios obtainable for the best version of invest- 
ment in each of the international sectors. 
The use we can make of this list is that we select the inter- 
national sector with the highest ratio and invest all available 
capital in this sector. With regard to international sectors this 
will mean complete specialization. To be sure there will be 
also additions to production in regional and national sectors 
involved. 
This complete specialization will be avoided whenever we 
add restrictions to the additional quantities that can be exported 
in any one international sectors. Whenever such a bound has 
been reached, the second-best international sector gets its turn. 
Complete specialization may also be avoided if we introduce 
an element of decreasing returns, not yet discussed, but realistic 
n agriculture and mining. It is not to be expected that it will 
be avoided by the introduction of indivisibilities, or increasing 
returns. But it may be avoided also if instead of restrictions 
to exportable quantities we introduce a price level of export 
goods negatively depending on quantities produced "z7 
The introduction of non-linear inputs brings in the pos- 
sibility that the effects on regional income of two projects are not 
31 Tinbergen - pag. g