Suppose a physical library has ten identical study rooms, to be used by one student at a time. Students must request a … See more

Counting semaphores are equipped with two operations, historically denoted as P and V (see § Operation names for alternative names). Operation V increments the semaphore S, and operation P decrement… See more

Consider a variable A and a boolean variable S. A is only accessed when S is marked true. Thus, S is a semaphore for A.
One can imagine a stoplight signal (S) just before a train station (A). In this case, if the signal is gr… See more

The canonical names V and P come from the initials of Dutch words. V is generally explained as verhogen ("increase"). Several explanations have been offered for P, including proberen ("to test" or "to try"), passeren ("… See more