$(m,p)$-isometric and $(m,\infty)$-isometric operator tuples on normed   spaces
  We generalize the notion of $m$-isometric operator tuples on Hilbert spaces in a natural way to normed spaces. This is done by defining a tuple analogue of $(m,p)$-isometric operators, so-called $(m,p)$-isometric operator tuples. We then extend this definition further by introducing $(m,\infty)$-isometric operator tuples and study properties of and relations between these objects. 
Philipp H. W. Hoffmann and Michael Mackey
math.FA math.OA