Holography tells that a theory with gravity in D-dimensions is equivalent to a field theory in D-1 on the boundary. Similarly, after the second string revolution, we know there are symmetries called dualities, pervading every superstring or M-theory. What is the symmetry principle and/or general invariance under these maps? And moreover, what would be the conserved quantity or Noether identity associated to these? Addendum: in classical mechanics, when you pass from a sistem with N d.o.f., to N-1 d.o.f. you get a momentum conservation from cyclic coordinate. What is the cyclic "coordinate" under a holography or duality map? If any...I mean, is there any known consequence after dimensional reduction. Of course, I suppose the trick is in the counting of the fields.