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Farmland Management
MINERVA superseeded IF/Prolog. Please see http://www.ifcomputer.co.jp/MINERVA for details.

We discontinued to sell IF/Prolog Dec 31. 2003. For current customers, we continue to provide professional support for IF/Prolog until Dec 31, 2008.

A farmer can choose to grow wheat or corn in his fields, each crop produces a different yield per hectare but also requires a different amount of time for its care. There is a limit to the maximum number of working days the farmer has available for these crops. The following IF/Prolog program calculates the maximum yield achievable from his 100 hectares and 40 working days. The yield of wheat pro acre is 2.5, while that of corn is 3.5. The time necessary for cultivating wheat compared with that for corn is 1:2. 

:-import(const_linear).


farm(Area,  WorkTime,  AreaCorn,  AreaWheat,  Yield)  :-
              corn(OutputCorn,  CostsCorn),
              wheat(OutputWheat,  CostsWheat),
              all_positive([AreaCorn,  AreaWheat]),
              Area  $>=  AreaCorn  +  AreaWheat,
              WorkTime  $>=  CostsCorn  *  AreaCorn +
                              CostsWheat  *  AreaWheat,
              linear_maximize(AreaCorn  *  OutputCorn  +
                               AreaWheat  *  OutputWheat,
                                        Yield).
corn(0r5/2,  0r1/3).
wheat(0r7/2,  0r2/3).


[user]  ?-  farm(100,40,AreaCorn,AreaWheat,Yield).
AreaCorn             =  80
AreaWheat            =  20
Yield     =  270
yes

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