question: private List < Node > possibleParents ( Node x , List < Node > nodes , IKnowledge knowledge ) { List < Node > possibleParents = new LinkedList < > ( ) ; String _x = x . getName ( ) ; for ( Node z : nodes ) { String _z = z . getName ( ) ; if ( possibleParentOf ( _z , _x , knowledge ) ) { possibleParents . add ( z ) ; } } return possibleParents ; }
target:  Removes from the list of nodes any that cannot be parents of x given the background knowledge.