Two suggestions: 1) Use the joda time library for representing date/time if possible. It's bundled with droole because of fusion and is much easier to work with. 2) If you use some "ugly" pattern often, define a custom operator to makw the syntax cleaner. GreG On May 7, 2010, at 11:13, Bill Hainaut <billhainaut(a)gmail.com&gt; wrote: This seems to do the trick. I hate the ugly date math, but otherwise, I'm satisfied: $s : SeatAssignment ( ) $mission : CrewSegment( taskBeingTested == true ) $total : Number( doubleValue > 56 ) from accumulate( CrewSegment( personId == $s.personId, endDate.time <= $mission.endDate.time, startDate.time > ($mission.endDate.time - (7L * 24L * 60L * 60L * 1000L)), $crewHours : crewHours ), sum( $crewHours ) ) Bill Hainaut wrote: Drools Experts: I have a list of the following fact objects sent to my rules: CrewSegment Date startDate Date endDate double crewHours int personId along with an object to designate seats: SeatAssignment int seatId int personId Here is the rule I want to enforce in English: No crew member (uniquely identified by personId) can have more than 56 hours of total crewHours in any 7 day period. The rule I've written so far is: when $s : SeatAssignment ( ) $total : Number( doubleValue > 56 ) from accumulate( CrewSegment( personId == $s.personId, $crewHours : crewHours ), sum( $crewHours ) ) This rule nicely catches any instance where more than 56 hours are committed by a person, but does not limit the time period to 7 days. How do I limit the search to be sure that it is 56 hours WITHIN 7 days, and not just 56 hours total over ANY time period? Thanks in advance for any help you can provide!!! Bill _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Rule-syntax-to-accumu... Sent from the Drools - Dev mailing list archive at Nabble.com. _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev