The Pauli principle revisited
  By the Pauli exclusion principle no quantum state can be occupied by more than one electron. One can put it as a constraint on the electron density matrix that bounds its eigenvalues by 1. Shortly after its discovery the Pauli principle has been replaced by skew symmetry of a multi-electron wave function.   In this paper we solve a longstanding problem about the impact of this replacement on the electron density matrix, that goes far beyond the original Pauli principle. 
M. Altunbulak, A. Klyachko