Sequential mode first evaluates all of the LHS. Which results in a single conflict set. It then evaluates the conflict set in salience and rule order. Modifying values will not result in the LHS being re-evaluated.Ross H wrote:You might need to think about how the rules engine does it job. The first part is setting up the network to match your conditions, the second is then executing the consequences of those matched facts. What your seeing here is the first part finding nulls. So you need to make sure that all your facts are fully populated if they are being checked in the conditions, or you need to add conditions that check for null. I think salience does not come into play until after the facts have been matched.It seems I have misunderstood the documentation- the sequential mode (https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/docs/drools-expert/html_single/index.html#d0e1809) 3.3.7.1: "Order the Rules by salience and position in the ruleset (by setting a sequence attribute on the rule terminal node)."