public boolean addSvf(OwlClass targetClass){
  targetClass.addSvfRestriction(this);
  return svfClasses.add(targetClass);
}

public boolean addSvf ( OwlClass targetClass ) { targetClass . addSvfRestriction ( this ) ; return svfClasses . add ( targetClass ) ; }
add " somevaluesfrom c " information , and tell c to point back here .
