Hello, all, I've designed a simple generic problem to demonstrate our issue. (We are building a system having difficulty designing fact classes that do not produce infinite loops and wanted input/discussion from Drools users.) I'd like to assert Mothers and Fathers to an engine and then ensure that each mother and father produces exactly one child, where the child has the father's first and last name and the mother's middle name. Of course, I could achieve this in one rule, but I like to break out the rules so that as my requirements change I can change a single rule (for example, suppose the requirement changes such that the child should not get its middle name set to its mother's but its mother's last name). My object model is Mother, Father, and Child, but the following rules produce an infinite execution loop in the rules engine. I know why this is; it is because i have to update($child) whenever I modify it--even if I modify a single property on the child. All other rules that use the child in their LHS will re-fire thinking that the entire fact has changed. The way to fix this is to not use the Mother, Father, and Child objects as mutable facts but introduce other Classes that represent the *properties* first, middle, and last name... in this case I would produce fact "new MiddleName( $child, "Sue" )", for example. But this results in less-readable rules. Why can't Drools allow us to indicate property-updates (and track facts at the property-level, not at the class level)? Or is there another suggestion to offer? Here are the rules: ===== rule "Every mother and father produce a child" no-loop when $mother : Mother( ) $father : Father( ) eval( $mother.getPartner() == $father ) then Child child = new Child($mother.getId() + "-" + $father.getId()); child.setMother($mother); child.setFather($father); insertLogical( child ); end rule "Every child gets his/her father's first and last name" no-loop when $father : Father( ) $child : Child( father == $father ) then $child.setFirst($father.getFirst()); $child.setLast($father.getLast()); update($child); end rule "Every child gets his/her mother's middle name" no-loop when $mother : Mother( ) $child : Child( mother == $mother ) then $child.setMiddle($mother.getMiddle()); update($child); end =====