Hello, Is it possible to write a rule that specifies two objects hold on to each other? When saving the following snippet, the Eclipse IDE complains <<Unable to return Declaration for identifier 'a'>>: rule "purple-eyed_ozies" when p : Person(eye_color == "purple", nm : name, address == a ) a : Address( person == p, country == "oz") then System.out.println( "Found purple-eyed ozian: "+nm ); end If I can avoid it, I would rather not use keys or object ids to implement the association or link. For whatever it may be worth, I am trying to duplicate the following experiment that works in JESS: (deftemplate person (slot name) (slot eye_color) (slot address) ) (deftemplate address (slot person) (slot street) (slot city) (slot zip) (slot country) ) (deffunction people () (bind ?p (assert(person (name rincewind) (eye_color octarine)))) (bind ?a (assert(address (country klatch) (person ?p)))) ; Yes, when we break the bidirectional relationship ; by commenting out the next line, rincewind is no longer found. (modify ?p (address ?a)) (bind ?p (assert(person (name atuin) (eye_color purple)))) (bind ?a (assert(address (country klatch) (person ?p)))) (modify ?p (address ?a)) (bind ?p (assert(person (name barney) (eye_color purple)))) (bind ?a (assert(address (country oz) (person ?p)))) (modify ?p (address ?a)) (bind ?p (assert(person (name scarecrow) (eye_color octarine)))) (bind ?a (assert(address (country oz) (person ?p)))) (modify ?p (address ?a)) ) (defrule purple-eyed_ozies ?p <- (person (eye_color purple) (name ?nm) (address ?a)) ?a <- (address (person ?p) (country oz)) => (printout t "Found purple-eyed ozian: " ?nm " ")) (defrule octarine-eyed_klatchians ?a <- (address (country klatch) (person ?p)) ?p <- (person (eye_color octarine) (name ?nm) (address ?a)) => (printout t "Found octarine-eyed klatchian: " ?nm " ")) (people) (run) (exit) Thank you, Art