V and P meaning

[brabo]

Hi,

I am very much enjoying your book so far, I notice however you do mention in a footnote that V and P are not entirely meaningless if you speak dutch. I fail to see however why you do not mention their meanings? It would make sense to explain V means vrijgeven (release) and P means proberen (try). It would make for everyone who reads your book clear that V and P do have an excellent meaning vs not important at all. It would also be nice especially given you say Dijkstra realised a meaningless name is better than a misleading name. I highly doubt that was his reasoning here...

Greetings, and many thanks for the otherwise excellent book!

[AllenDowney]

Thanks for this comment.

Here's what Wikipedia has on the topic:

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"),[4] passeren ("pass"), and pakken ("grab"). Dijkstra's earliest paper on the subject[2] gives passering ("passing") as the meaning for P, and vrijgave ("release") as the meaning for V. It also mentions that the terminology is taken from that used in railroad signals. Dijkstra subsequently wrote that he intended P to stand for the portmanteau prolaag,[5] short for probeer te verlagen, literally "try to reduce," or to parallel the terms used in the other case, "try to decrease."[6][7][8]

So there is no consensus on what the abbreviations stand for, and in most writings Dijkstra made no effort to explain. I conjecture that he did not intend the names to be mnemonic, even for Dutch speakers.

And I do think that meaningless is better than misleading (even if that is not what Dijkstra had in mind). The problem with alternative like signal and wait is that they only apply to some uses of semaphores.

But I will consider revising this section to make it clearer that Dijkstra's intent on this is not known.

On Sun, Apr 2, 2017 at 4:33 PM, brabo [email protected] wrote:

Hi,

I am very much enjoying your book so far, I notice however you do mention in a footnote that V and P are not entirely meaningless if you speak dutch. I fail to see however why you do not mention their meanings? It would make sense to explain V mean vrijgeven (release) and P means proberen (try). It would make for everyone who reads your book clear that V and P do have an excellent meaning vs not important at all. It would also be nice especially given you say Dijkstra realised a meaningless name is better than a misleading name. I highly doubt that was his reasoning here...

Greetings, and many thanks for the otherwise excellent book!

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