Perspectives and completely positive maps
  We study the filtering of the perspective of a regular operator map of several variables through a completely positive linear map. By this method we are able to extend known operator inequalities of two variables to several variables; with applications in the theory of operator means of several variables. We also extend Lieb-Ruskai's convexity theorem from two to $ n+1 $ operator variables. 
Frank Hansen
math-ph math.MP