Comment on "Entropy and Wigner function"
  In a recent paper [PRE 62, 4665 (2000)] (quant-ph/0203102) Manfredi and Feix proposed an alternative definition of quantum entropy based on Wigner phase-space distribution functions and discussed its properties. They proposed also some simple rules to construct positive-definite Wigner functions which are crucial in their discussion. We show, however, that the main results obtained and their discussion are incorrect. 
J. J. Wlodarz