Mutual Exclusion - If process Pi is executing in its critical section, then no other processes can be executing in their critical sections
Progress - If no process is executing in its critical section
exist some processes that wish to enter their critical section
the selection of the processes that will enter the critical section next cannot be postponed indefinitely
Bounded Waiting - A bound must exist on the number of times that other processes are allowed to enter their critical sections
after a process has made a request to enter its critical section and before that request is granted