Class IloResourceConstraint

Instances of the class IloResourceConstraint are resource constraints.

This class inherits from the IBM® ILOG® Concert Technology class IloConstraint. That class is documented in the IBM ILOG Concert Technology Reference Manual.

Instances of this class are created by these member functions:

• IloActivity::requires
• IloActivity::provides
• IloActivity::consumes
• IloActivity::produces
• IloActivity::requiresNot

The five elements of a resource constraint are an activity, an alternative resource set, a constant or variable demand, a time extent, and a rounding mode.

A resource constraint enforces the fact that on a certain time interval, exactly one resource from a set of alternatives that make up an instance of IloAltResSet is used to process the activity. The class IloActivity offers a set of member functions to create a resource constraint.

The demand type depends upon the resource. For example, a discrete capacity resource or a reservoir needs a positive numerical demand. The demand type for a state resource is a state or a set of states.

The time extent declares the period of time over which the availability of the resource is affected by the activity. Usually, the default value of the time extent is sufficient, since most activities will “require” a discrete capacity or a state resource from the start to the end of the activity. So in most cases, the time extent does not need to be declared. An activity can either produce or consume a reservoir.

The rounding mode tells the solver how to manage the use of the time buckets. Depending on the rounding mode, an activity that partially overlaps a time bucket is considered to either require the resource over the entire time bucket, or not require the resource during the time bucket at all.

Note that for resource constraints on continuous reservoirs, the time extent and the rounding mode have no meaning and are not used. This is because the time step of a timetable for a continuous reservoir is 1, so the returned resource constraint has no inward/outward rounding mode. Its time extent, which does not match any case of the enumeration IloTimeExtent, is not defined either.

The alternative resource set specifies the set of resources from which one resource must be selected. If the resource constraint has only one possible resource, then it requires an alternative resource set with a single element.

In order to better model interaction between activities and resources, it is possible to attach a specific calendar on a resource constraint. In such a case, the calendar of the resource constraint will subsume the calendar possibly attached to the corresponding resource. That is, even if a calendar is defined on the resource, it is not taken into account when a calendar is specified on the resource constraint.

The member functions of the class IloResourceConstraint allow retrieval of this data. In addition, the class IloResourceConstraint offers member functions to constrain the relative position of activities on the resource.

For more information, see Temporal Relations.

This member function returns the activity of the invoking resource constraint.

This member function returns the instance of IloAltResSet associated with the invoking constraint. If the resource constraint was constructed with a single resource, rather than an IloAltResSet, this function returns an IloAltResSet containing only that resource. The alternative resource set, denoted ARS here, is local to the invoking resource constraint. That is, it is not shared with any other resource constraint unless a new resource constraint is subsequently as requiring ARS.

This member function returns the calendar attached to the invoking resource constraint, if such an object exists.

This member function returns the required or provided quantity of the invoking resource constraint.

This member function returns the maximal required or provided quantity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the minimal required or provided quantity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the variable representing the required or provided quantity of the invoking resource constraint.

This member function returns the longest duration of the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the shortest duration of the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the latest end time of the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the earliest end time of the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the next resource constraint that affects the availability of the resource after the invoking resource constraint.

This member function returns the longest processing time for the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the shortest processing time for the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the resource of the invoking resource constraint. This method throws an exception if the invoking resource constraint has an alternative resource set that does not contain exactly one element.

This function returns the instance of IloShape associated with the resource constraint.

This member function returns the latest start time of the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the earliest start time of the activity of the invoking resource constraint assuming resource is the selected resource.

This member function returns the required state of the invoking resource constraint.

This member function returns the required set of states of the invoking resource constraint.

This member function returns the variable representing the required set of states of the invoking resource constraint.

This member function returns the variable representing the required state of the invoking resource constraint.

This member function returns the time extent of the invoking resource constraint.

This function returns IloTrue if and only if a next relation has been added with the member function IloResourceConstraint::setNext.

This member function returns IloTrue if a calendar has been attached to the invoking resource constraint. Otherwise, it returns IloFalse.

This function returns IloTrue if and only if there exists a unique resource constraint, ct, that has been constrained to be next after the invoking resource constraint with the member function IloResourceConstraint::setNext.

This function returns IlcTrue if a shape has been associated with the resource constraint

This member function returns IloTrue if and only if the invoking resource constraint indicates that a quantity (and thus not a state) is required or provided.

This member function returns IloTrue if and only if the occupancy of the resource by the invoking constraint is to be rounded inward towards the nearest valid time that corresponds to a time step. This rounding is important only when one of the resource usage enforcement intervals of the resource has a time step greater than 1 (one).

This member function returns IloTrue if and only if the invoking constraint was constructed by the member function IloActivity::requiresNot

This member function returns IloTrue if and only if the invoking constraint was constructed by one of these member functions: IloActivity::provides or IloActivity::produces.

This member function returns IloTrue if resource cannot be selected for the activity associated with the invoking resource constraint (see member function IloResourceConstraint::setRejected). Otherwise, it returns IloFalse.

This member function returns IloTrue if resource must be selected by the invoking constraint (see member function IloResourceConstraint::setRejected). Otherwise, it returns IloFalse.

This member function returns IloTrue if and only if the invoking resource constraint has been constrained to be a setup resource constraint with the member function IloResourceConstraint::setSetup.

This member function returns IloTrue if and only if the invoking resource constraint indicates that a single state (and thus not a quantity or one of a set of states) is required.

This member function returns IloTrue if and only if the invoking resource constraint indicates that one of a set of states (and thus not a quantity or a single state) is required.

This member function returns IloTrue if and only if a successor relation has been added with the member function IloResourceConstraint::setSuccessor.

This member function returns IloTrue if and only if the invoking resource constraint has been constrained to be a teardown resource constraint with the member function IloResourceConstraint::setTeardown.

This member function returns IloTrue if and only if the invoking resource constraint has a variable representing the required quantity or state or provided quantity.

This function associates an instance of IloVariableSlopeShape with the resource constraint. Shapes are only available on continuous reservoirs. If the resource constraint already has a shape, that shape is discarded and replaced by the newly created one. An exception will be thrown at extraction time if the minimal value of the slope variable is strictly negative.

This function removes the instance of IloShape associated with the resource constraint.

This member function creates and returns a constraint that specifies that resource must be selected for the invoking resource constraint.

The fact that a given resource r must not be selected for a resource constraint rct can be expressed by the negation of this constraint, as follows:

 model.add(!rct.select(r))

This member function attaches the calendar calendar to the invoking resource constraint. Notice that calendars can be shared between resource constraints, and that setCalendar does not imply that a local copy of the calendar is made. One should be aware of the fact that any change to a shared calendar (using IloCalendar member functions with the calendar that comes from getCalendar) applies to all resource constraints sharing the calendar.

This member function states that if resource is the selected resource, then the maximal required or provided quantity of the invoking resource constraint is max.

This member function states that if resource is the selected resource, then the minimal required or provided quantity of the invoking resource constraint is min.

This member function states that if resource is the selected resource, the longest duration of the activity of the invoking resource constraint is max.

This member function states that if resource is the selected resource, then the shortest duration of the activity of the invoking resource constraint is min.

This member function states that if resource is the selected resource, then the latest end time of the activity of the invoking resource constraint is max.

This member function states that if resource is the selected resource, then the earliest end time of the activity of the invoking resource constraint is min.

This member function states that if the invoking resource constraint and ct affect the same resource, then ct is next after the invoking resource constraint. There cannot exist any other resource constraint that affects the availability of the resource and starts or finishes between the end of the invoking resource constraint and the start of ct.

At extraction time if there is an empty intersection between the alternative resource set for the invoking resource constraint and the alternative resource set for ct, this function has no effect, as the condition that the two resource constraints must affect the same resource cannot be true.

This member function states that ct is not next after the invoking resource constraint. This means that if the invoking resource constraint and ct both affect the availability of the resource, then there must be another resource constraint that affects the availability of the resource and it starts or finishes between the end of the invoking resource constraint and the start of ct.

At extraction time if there is an empty intersection between the alternative resource set for the invoking resource constraint and the alternative resource set for ct, this function has no effect, as the condition that the two resource constraints must affect the same resource cannot be true.

This member function states that the invoking resource constraint is not a setup resource constraint. This means that if the invoking resource constraint affects the availability of the resource, there must be a different resource constraint previous to it that also affects the availability of the resource.

This member function states that the invoking resource constraint is not a teardown resource constraint. This means that if the invoking resource affects the availability of the resource, then there must be a different resource constraint that also affects the availability of the resource and occurs after the invoking resource constraint.

This member function states that if resource is the selected resource, then the longest processing time for the activity of the invoking resource constraint is max.

This member function states that if resource is the selected resource, the shortest processing time for the activity of the invoking resource constraint is max.

This member function states that it is not possible for resource to be selected. If resource is not a member of the alternative resource set of the invoking resource constraint, this method has no effect.

This member function states that resource must be selected for the activity associated with the invoking constraint. If resource is not a member of the alternative resource set of the invoking resource constraint, this method will result in an inconsistent model. Any attempt to solve such a model will fail.

This member function states that the invoking resource constraint is a setup resource constraint. This means that if the invoking resource constraint affects the availability of the resource, no other resource constraint that affects the availability of the resource can be previous to it.

This member function states that if resource is the selected resource, the latest start time of the activity of the invoking resource constraint is max.

This member function states that if resource is the selected resource, the earliest start time of the activity of the invoking resource constraint is min.

This member function states that the invoking resource constraint has the resource constraint ct as successor. This means that if the invoking resource constraint and ct both affect the availability of the resource, then the activity of ct is constrained to execute after the activity of the invoking resource constraint.

At extraction time if there is an empty intersection between the alternative resource set for the invoking resource constraint and the alternative resource set for ct, this function has no effect, as the condition that the two resource constraints must affect the same resource cannot be true.

This member function states that the invoking resource constraint is a teardown resource constraint. This means that if the invoking resource constraint affects the availability of the resource, then no resource constraint can exist that affects the availability of the resource after the invoking resource constraint.

This member function removes all information regarding the next relation between the invoking resource constraint and ct. That is, the information specified by both of the member functions IloResourceConstraint::setNext and IloResourceConstraint::setNotNext is removed from the model.

This member function states that resource is a possible resource for the activity associated with the invoking constraint, but not necessarily the one selected. This member function removes the information added to the model by the IloResourceConstraint::setSelected and IloResourceConstraint::setRejected member functions.

This member function removes all setup information from the invoking resource constraint. That is, this member function removes all information added to the model by the member functions IloResourceConstraint::setSetup and setNotSetup.

This member function removes all information regarding the successor relation between the invoking resource constraint and ct. That is, the information specified by the member function setSuccessor(ct) is removed from the model.

This member function removes all teardown information from the invoking resource constraint. That is, this member function removes all information added to the model by the member functions IloResourceConstraint::setTeardown and setNotTeardown.