The Saturation of Several Universal Inequalities in   Information-Processing
  In this paper, we characterize the saturation of four universal inequalities in quantum information theory, including a variant version of strong subadditivity inequality for von Neumann entropy, the coherent information inequality, the Holevo quantity and average entropy inequalities. These results shed new light on quantum information inequalities. 
Lin Zhang and Junde Wu and Shao-Ming Fei
quant-ph math-ph math.MP