requires
requires |
Purpose
Sets the minimal and maximal amount of resource required by a task for a particular resource.
A task requires some amount of processing power of a resource when this amount must be made available for the execution of the task. The resource requirement is considered as renewable which means that whenever the tasks ends the processing power that was required is still available for processing other tasks. Note that a minimal amount of 0 is possible thus allowing modelisation of alternative resources. The type of resource requirement can be defined in several ways:
A task requires some amount of processing power of a resource when this amount must be made available for the execution of the task. The resource requirement is considered as renewable which means that whenever the tasks ends the processing power that was required is still available for processing other tasks. Note that a minimal amount of 0 is possible thus allowing modelisation of alternative resources. The type of resource requirement can be defined in several ways:
- By specifying a resource and a constant requirement parameter 'requirement'. In this case the resource requirement is constant other the execution of the task.
- By specifying a resource and a minimal 'minReq' and maximal 'maxReq' requirement parameters: In this case the resource requirement is a decision variable but is constant other the execution of the task.
- By specifying a cpresusage 'usage' (see resusage for further detail).
- By a set of alternative cpresusage 'optUsages': This makes it possible to model alternative resources. The type of resource requirement is defined by the resource usage passed in argument (see resusage for further detail).
- By a set of alternative cpresusage 'optUsages', a minimal 'minalt' and a maximal 'maxalt' number of alternative resources that are required: Between [minalt..maxalt] alternative requirements from the set will be active which means that several resources will be chosen as requirements by the task. The type of resource requirement is defined by the resource usage passed in argument (see resusage for further detail).
Synopsis
procedure requires(task:cptask, requirement:integer, resource:cpresource)
procedure requires(task:cptask, minReq:integer, maxReq:integer, resource:cpresource)
procedure requires(task:cptask, usage:cpresusage)
procedure requires(task:cptask, optUsages:set of cpresusage)
procedure requires(task:cptask, optUsages:set of cpresusage, minalt:integer, maxalt:integer)
Arguments
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task
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the task
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requirement
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constant positive resource consumption
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minReq
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minimal resource requirement
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maxReq
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maximal resource requirement
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resource
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the resource to be required
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usage
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the resource usage
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optUsages
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the set of alternatives resource requirements
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minalt
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minimal number of resources that must be required
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maxalt
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maximal number of resources that may be required
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Example
The following example illustrates this:
model "Producer Consumer"
uses "kalis"
declarations
Masonry, Carpentry, Roofing, Windows, Facade, Garden, Plumbing,
Ceiling, Painting, MovingIn : cptask ! Declaration of tasks
money_available : cpresource ! Resource declaration
end-declarations
! 'money_available' is a cumulative resource with max. amount of 29$
set_resource_attributes(money_available,KALIS_DISCRETE_RESOURCE,29)
! Limit resource availability to 20$ in the time interval [0,14]
setcapacity(money_available, 0, 14, 20)
! Setting the task durations and predecessor sets
set_task_attributes(Masonry , 7 )
set_task_attributes(Carpentry, 3, {Masonry} )
set_task_attributes(Roofing , 1, {Carpentry} )
set_task_attributes(Windows , 1, {Roofing} )
set_task_attributes(Facade , 2, {Roofing} )
set_task_attributes(Garden , 1, {Roofing} )
set_task_attributes(Plumbing , 8, {Masonry} )
set_task_attributes(Ceiling , 3, {Masonry} )
set_task_attributes(Painting , 2, {Ceiling} )
set_task_attributes(MovingIn , 1, {Windows,Facade,Garden,Painting})
! Setting the resource consumptions
consumes(Masonry , 7, money_available )
consumes(Carpentry, 3, money_available )
consumes(Roofing , 1, money_available )
consumes(Windows , 1, money_available )
consumes(Facade , 2, money_available )
consumes(Garden , 1, money_available )
consumes(Plumbing , 8, money_available )
consumes(Ceiling , 3, money_available )
consumes(Painting , 2, money_available )
consumes(MovingIn , 1, money_available )
! Find the optimal schedule (minimizing the makespan)
if cp_minimize(getmakespan) then
cp_show_sol
else
writeln("No solution found")
end-if
end-model
Related topics
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