A rule like this:

rule R1
  when
    Cheese($type : type)
    not( Person( likes == $type, salary == null ) )

• insert Cheese
• Insert multiple Persons which don't match the rule (salary == null)
• Update one Person with non-related property Note:This fact has to be a "blocker" in rightTuple in NotNode
• Update the same Person to match the not (salary == 1000)
• Still 2 Persons don't match the condition so the rule should not fire. — However, the rule fires