IlcRankBackward

This function creates and returns a goal that ranks all resource constraints on a set of resources in anti-chronological order.

If its first argument is an instance of IlcResource, it considers all the resource constraints on that instance of IlcResource.
If its first argument is an instance of IlcSchedule, it considers all the resource constraints on instances of IlcResource in that schedule. The resource selector rSel selects the next resource. By default, that is, when no resource selector object is given, a resource selector defaultResSel defined as follows is used:

 IloSelector<IlcResource,IlcSchedule> defaultResSel = IlcResourceInScheduleSelector(s);
 sel.setPredicate(IlcResourceIsUnaryResourcePredicate(s) &&
		    !IlcResourceRankedPredicate(s));
 sel.setComparator(IlcResourceGlobalSlackEvaluator(s));

If the argument criterion is given, then this variable will be bound, if possible, to its maximal value at the end of the search.

The resource constraint selector rcSel selects the next resource constraint to be ranked last on a given resource given as first context to the selection function. By default, that is, when no IloSelector<IlcResourceConstraint> is given, a resource constraint selector defaultRCSel defined as follows is used:

 IloSelector<IlcResourceConstraint,IlcResource> defaultRCSel = IlcResourceConstraintInScheduleSelector(s);
 IlcTranslator<IlcActivity, IlcResourceConstraint> ac = IlcActivityResourceConstraintTranslator(s);
 sel.setPredicate(IlcResourceConstraintPossibleLastPredicate(s));
 sel.setComparator(IlcLexicalComposition(IlcCompareMax(IlcActivityEndMaxEvaluator(s)<<ac),
					   IlcCompareMax(IlcActivityEndMinEvaluator(s)<<ac)));

Note

WARNING This function assumes that all resources that are selected have been closed, that is, that no unknown resource constraints have yet to be posted. If you cannot close all resources, you should use a resource selector that selects only closed resources. In such a case, you should also handle the ranking of the resources that are not closed yourself.

Ranking is only well defined on unary and state resources. Therefore, your resource selector should contain an instance of IlcResourceIsUnaryResourcePredicate or IlcResourceIsStateResourcePredicate (or both, joined by a logical-OR).

Implementation

Here's how we could define the goal returned by the first version of the function.

 ILCGOAL2(IlcRankBackwardResource, IlcResource, resource,
 	 IloSelector<IlcResourceConstraint,IlcResource>, rcSel) {
   IlcResourceConstraint constraint;
   if (rcSel.select(constraint, resource))
     return IlcAnd(IlcTryRankLast(constraint), this);
   return 0;
 }

Here's how we could define the goal returned by the second version of the function:

 ILCGOAL3(IlcRankBackwardSchedule, IlcSchedule, schedule,
 	 IloSelector<IlcResource,IlcSchedule>, rSel,
 	 IloSelector<IlcResourceConstraint,IlcResource>, rcSel) {
   IlcResource resource;
   if (rSel.select(resource, schedule))
     return IlcAnd(IlcRankBackward(resource, rcSel), this);
   return 0;
 }

See IloSelector in the IBM ILOG Solver Reference Manual for more information.