Origins of P( ) and V( )

In Operating Systems, the Dutch Computer Scientist E. W. Dijkstra introduced a pair of synchronization primitives called P( ) and V( ).

To make them understandable, we sometimes called them Down( ) and Up( ), or Wait( ) and Signal( ), etc.

Students often wonder what they stand for. So I asked a colleague, Professor Gert Vegter from Groningen University in The Netherlands.

	...
	Concerning Dijkstra's semaphores:
	it's simple: P = Plantinga, V = Vegter (:-))
	
	In fact, P = Probeer ('Try')
	and V = Verhoog ('Increment', 'Increase by one').
	These are the operations embracing the critical section.
	Dijkstra introduced these ops in 1963. Attached are 1974 lecture notes bij
	Dijkstra explaining the PV mechanism. In dutch, unfortunately...
	('Over seinpalen' = 'On semaphores')
	
	Best regards,
	Gert