Hi, I have application similar to nurse rostering. You have projects, resources and dates. You assign resource on date to project (thus you have an assignment). Now, I have rule that is supposed to keep assignments "together". Most of the assignments are indeed kept together with some few but very nasty exceptions. I have attached the image (Schedule.png) to visualize this. In the image you see assignments for Project 9 being planed en block from 13. July till 20. July (green box at the bottom). But then there are couple of assignments (above, underlined in red on 2. January and on 22. February) totally "out of the row". I attempt to "pull" assignments together with this rule: rule "penalize assignment dispersion to goLive" when $project : Project(goLive != null) $furthestAssignment : Assignment(project == $project, interval != null, $project.goLive.compareTo(interval.end) >= 0) not Assignment(id > $furthestAssignment.id, project == $project, interval != null, $project.goLive.compareTo(interval.end) >= 0, distanceToGoLive >= $furthestAssignment.distanceToGoLive) then insertLogical( new IntConstraintOccurrence("penalizing assignment dispersion", ConstraintType.NEGATIVE_SOFT, $furthestAssignment.distanceToGoLive(), $project) ); end There are number of other rules. The ones checking hard constraints are trivial and I will just omit them, the soft constraint rules might have impact on this issue although unlikely (I removed all the other soft constraint rules and still got similar weird result). Here are the other rules: rule "penalize assignment with the resource without the capability required by project option" when $projectOption : ProjectOption() $penalizedAssignments : Number(intValue > 0) from accumulate ( Assignment($penalizedAssignment : this, project == $projectOption.project, resource != null, resource.capabilities not contains $projectOption.name), count($penalizedAssignment) ) then insertLogical( new IntConstraintOccurrence("there are assignments with the resource without the capability required by project option", ConstraintType.NEGATIVE_SOFT, $penalizedAssignments.intValue(), $projectOption, $penalizedAssignments) ); end rule "penalize assignment with the resource without the capability required by project constraint" when $projectConstraint : ProjectConstraint() $penalizedAssignments : Number(intValue > 0) from accumulate ( Assignment($penalizedAssignment : this, project == $projectConstraint.project, resource != null, resource.capabilities not contains $projectConstraint.name), count($penalizedAssignment) ) then insertLogical( new IntConstraintOccurrence("there are assignments with the resource without the capability required by project constraint", ConstraintType.NEGATIVE_SOFT, $penalizedAssignments.intValue(), $projectConstraint, $penalizedAssignments) ); end Am using Drools Planer 5.3. and biting out my teeth on this issue for about 3 moth already. Any help is worth half the kingdom to me right now. br Reinis