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"Dijkstra was probably a bit heavy on drugs or something (I think the official explanation is that P and V are the first letters in some Dutch words, but I pers

"Dijkstra was probably a bit heavy on drugs or something (I think the official explanation is that P and V are the first letters in some Dutch words, but I personally find the drug overdose story much more believable)." Quotes like this are why I always read what Linus has to say, regardless of whether the subject is relevant to my life in the slightest. Edit: Yes people, those Dutch words exist! I get it! I'm sure Linus was well aware of that when he made this remark. However, the point Linus was making (in a humorous way) was that like most computer scientists / mathematicians, Dijkstra was overly fond of obscure, single-letter names, which nobody ever intuitively understands. Whereas the names "up" and "down" (see the rest of Linus' quote) are far more intuitive. Personally, I would argue that "hold" and "release" convey the intent in a clearer, more abstract way.

tomp 12y ago
Me too. I just love this guy. Sure, some people find him insulting, but I call that "funny".
otherusername 12y ago
To say that a mathematician doesn't intuitively understand single-letter names would be like saying a programmer doesn't intuitively understand a keyboard. Dijkstra was a computer scientist in times where being a computer scientist meant you were basically a mathematician with a specialty. Semaphores were first introduced by him in one of his early EWDs (EWD35, http://www.cs.utexas.edu/users/EWD/ewd00xx/EWD35.PDF http://www.cs.utexas.edu/users/EWD/ewd00xx/EWD35.PDF). At the time of EWD35, his EWDs were non-official musings, written in Dutch, intended to be shared amongst interested colleagues and such. It's not like he was writing a scientific paper. I don't think Torvalds really meant anything much by it. He's just trying to be funny.
drcomputer 12y ago
> most computer scientists / mathematicians, Dijkstra was overly fond of obscure, single-letter names, which nobody ever intuitively understand If you use a word too common, it's too easy to confuse the definition of that word with the definition of its use in a different context. You must not understand the pain of reading two mathematical books and trying, with the utmost sincerity, to figure out whether the authors are actually using the words the same (such as set, relation, abstraction, object, even things like function). There's the distinct definition, and there is the contextual use, which can theoretically differ for everyone depending on the origin path of native language. You can never know if someone is altering the definition or discovering / describing something new, and they are using the wrong word. Discovering the perfect word for the concept you construct in code or math is an art.
outworlder 12y ago
> "Dijkstra was probably a bit heavy on drugs or something (I think the official explanation is that P and V are the first letters in some Dutch words, but I personally find the drug overdose story much more believable)." I personally have made remarks that were WAY more potentially offensive than that, verbally, with friends. But, accusing Dijkstra of being a drug user, on the Linux kernel mailing list, from a @transmeta address? That's grounds for termination in many companies, even if you don't get lawyers involved. I think he's only able to get away with it because he's Linus.
- ramblerman 12y ago
  I'd argue 'false drama' is the real culprit. A bit like your comment is adding to this thread.
- ANTSANTS 12y ago
  Technically, you're right. Today, any junior employee that made a joke like that would be crucified and practically blacklisted from the industry. What you should be thinking, however, is not "why does Linus get away with saying things like that?" but rather "why do I consider it normal for someone's livelihood to be permanently destroyed over a stupid joke?"
  - GFK_of_xmaspast 12y ago
    What do you think an appropriate response is?
    - jpitz 12y ago
      How about public shaming instead of the destruction of a career?
      - ANTSANTS 12y ago
        They're one and the same in this witch-hunt culture.
      - 12y ago
learnstats2 12y ago
> However, the point Linus was making (in a humorous way) was that like most computer scientists / mathematicians, Dijkstra was overly fond of obscure, single-letter names, which nobody ever intuitively understands. If he was making this point, I find it ironic, considering that the purpose of the post is to explain the distinction between two obscure, poorly-named technical words, which nobody ever intuitively understands.
- viraptor 12y ago
  Hi, I'm nobody. You use spinlock to spin in place until you can get the lock. You wait at semaphores. Seems very intuitive to me.
  - learnstats2 12y ago
    semaphore (ˈsɛməˌfɔː) n 1. (Telecommunications) an apparatus for conveying information by means of visual signals, as with movable arms or railway signals, flags, etc 2. (Telecommunications) a system of signalling by holding a flag in each hand and moving the arms to designated positions to denote each letter of the alphabet vb 3. (Telecommunications) to signal (information) by means of semaphore which definition fits your understanding that you 'wait'? It's not a good name.
    - viraptor 12y ago
      There are more meanings for semaphore: https://en.wikipedia.org/wiki/Railway_semaphore_signal https://en.wikipedia.org/wiki/Railway_semaphore_signal Edit: Ok, actually that could be within your first meaning. But the practical result for railway semaphores is that one of their uses is to stop trains from entering a blocked segment.
      - couchand 12y ago
        It's actually quite reasonable to complain about the use of the term semaphore here. As you recognize, stopping the train is only one of their uses. Railway signals can convey many different types of information about the state of the track, not just free/blocked. And moreover, a semaphore is just a specific type of railway signal, one with a pivoting arm. It's very hard to see how a pivoting arm is at all related to the CS concept.

tomp 12y ago

Me too. I just love this guy. Sure, some people find him insulting, but I call that "funny".

otherusername 12y ago

To say that a mathematician doesn't intuitively understand single-letter names would be like saying a programmer doesn't intuitively understand a keyboard. Dijkstra was a computer scientist in times where being a computer scientist meant you were basically a mathematician with a specialty. Semaphores were first introduced by him in one of his early EWDs (EWD35, http://www.cs.utexas.edu/users/EWD/ewd00xx/EWD35.PDF http://www.cs.utexas.edu/users/EWD/ewd00xx/EWD35.PDF). At the time of EWD35, his EWDs were non-official musings, written in Dutch, intended to be shared amongst interested colleagues and such. It's not like he was writing a scientific paper. I don't think Torvalds really meant anything much by it. He's just trying to be funny.

drcomputer 12y ago

> most computer scientists / mathematicians, Dijkstra was overly fond of obscure, single-letter names, which nobody ever intuitively understand If you use a word too common, it's too easy to confuse the definition of that word with the definition of its use in a different context. You must not understand the pain of reading two mathematical books and trying, with the utmost sincerity, to figure out whether the authors are actually using the words the same (such as set, relation, abstraction, object, even things like function). There's the distinct definition, and there is the contextual use, which can theoretically differ for everyone depending on the origin path of native language. You can never know if someone is altering the definition or discovering / describing something new, and they are using the wrong word. Discovering the perfect word for the concept you construct in code or math is an art.

outworlder 12y ago

> "Dijkstra was probably a bit heavy on drugs or something (I think the official explanation is that P and V are the first letters in some Dutch words, but I personally find the drug overdose story much more believable)." I personally have made remarks that were WAY more potentially offensive than that, verbally, with friends. But, accusing Dijkstra of being a drug user, on the Linux kernel mailing list, from a @transmeta address? That's grounds for termination in many companies, even if you don't get lawyers involved. I think he's only able to get away with it because he's Linus.

ramblerman 12y ago
I'd argue 'false drama' is the real culprit. A bit like your comment is adding to this thread.
ANTSANTS 12y ago
Technically, you're right. Today, any junior employee that made a joke like that would be crucified and practically blacklisted from the industry. What you should be thinking, however, is not "why does Linus get away with saying things like that?" but rather "why do I consider it normal for someone's livelihood to be permanently destroyed over a stupid joke?"
- GFK_of_xmaspast 12y ago
  What do you think an appropriate response is?
  - jpitz 12y ago
    How about public shaming instead of the destruction of a career?
    - ANTSANTS 12y ago
      They're one and the same in this witch-hunt culture.
    - 12y ago

learnstats2 12y ago

> However, the point Linus was making (in a humorous way) was that like most computer scientists / mathematicians, Dijkstra was overly fond of obscure, single-letter names, which nobody ever intuitively understands. If he was making this point, I find it ironic, considering that the purpose of the post is to explain the distinction between two obscure, poorly-named technical words, which nobody ever intuitively understands.

viraptor 12y ago
Hi, I'm nobody. You use spinlock to spin in place until you can get the lock. You wait at semaphores. Seems very intuitive to me.
- learnstats2 12y ago
  semaphore (ˈsɛməˌfɔː) n 1. (Telecommunications) an apparatus for conveying information by means of visual signals, as with movable arms or railway signals, flags, etc 2. (Telecommunications) a system of signalling by holding a flag in each hand and moving the arms to designated positions to denote each letter of the alphabet vb 3. (Telecommunications) to signal (information) by means of semaphore which definition fits your understanding that you 'wait'? It's not a good name.
  - viraptor 12y ago
    There are more meanings for semaphore: https://en.wikipedia.org/wiki/Railway_semaphore_signal https://en.wikipedia.org/wiki/Railway_semaphore_signal Edit: Ok, actually that could be within your first meaning. But the practical result for railway semaphores is that one of their uses is to stop trains from entering a blocked segment.
    - couchand 12y ago
      It's actually quite reasonable to complain about the use of the term semaphore here. As you recognize, stopping the train is only one of their uses. Railway signals can convey many different types of information about the state of the track, not just free/blocked. And moreover, a semaphore is just a specific type of railway signal, one with a pivoting arm. It's very hard to see how a pivoting arm is at all related to the CS concept.