Observe: rule "Bill Status" salience 100 when p :- exists Bill( paid == true ) then System.out.println( "There are " + (p ? "some" : "no") + " paid bills." ); end rule "Pay Bills" when $bill: Bill( paid == false ) then System.out.println( "Paying " + $bill.getAmount() ); modify( $bill ){ setPaid( true ) } end There are three unpaid Bills inserted, then fireAllRules(): There are no paid bills. Paying 3000 There are some paid bills. Paying 2000 Paying 1000 -W