Hi, I have been playing around with the optaplanner library for the past couple of weeks trying to learn a bit of the basics. I have been making some progress but I have a simple variation I am trying to accomplish to the stock CurriculumCourse example and am hitting a wall. What I am trying to do is modify the CurriculumCourse example to also allow the teachers to be planning variables. I plan on extending it to give constraints on which courses individual teachers can teach, but to start I am just assuming each teacher can teach any class to make things easier. - First I tried to add the Course entity as a second planning entity with the teacher being a PlanningVariable but keep on running into an exception based on the solver configuration java.lang.IllegalArgumentException: The entityPlacerConfig (QueuedEntityPlacerConfig(null, null)) has no entitySelector configured and because there are multiple in the planningEntityClassSet ([class org.optaplanner.examples.curriculumcourse.domain.Lecture, class org.optaplanner.examples.curriculumcourse.domain.Course]), it can not be deducted automatically. at org.optaplanner.core.config.constructionheuristic.placer.EntityPlacerConfig.deduceEntityDescriptor(EntityPlacerConfig.java:43) I can't seem to figure out where the entitySelector is missing or what the entityPlacer is used for or where it is configured. I have read that multiple planning entities are possible, but can't determine how to get this *simple* example to work. - Second I tried to see if i could move the teacher planning variable to the Lecture planningEntity, but cant figure out a way to keep all of the lectures of one course stuck with the same teacher. I dont believe I can change other planning entities on my own when one is updated. I am still new to looking at these problems and determining the best model to fit it, so hoping someone might have some tips/help on how to handle this scenario. Thanks in advanced, -- View this message in context: http://drools.46999.n3.nabble.com/CurriculumCourse-extending-for-multiple... Sent from the Drools: User forum mailing list archive at Nabble.com.