Relative Convexity and Its Applications
  We discuss a rather general condition under which the inequality of Jensen works for certain convex combinations of points not all in the domain of convexity of the function under attention. Based on this fact, an extension of the Hardy-Littlewood-P\'olya theorem of majorization is proved and new insight is given into the problem of risk aversion in mathematical finance. 
Constantin P. Niculescu and Ionel Roventa
math.CA