The Separation of Duty with Privilege Calculus
  This paper presents Privilege Calculus (PC) as a new approach of knowledge representation for Separation of Duty (SD) in the view of process and intents to improve the reconfigurability and traceability of SD. PC presumes that the structure of SD should be reduced to the structure of privilege and then the regulation of system should be analyzed with the help of forms of privilege. 
Chenggong Lv, Jun Wang, Lu Liu, and Weijia You