Because this suggestion was so unpopular, I have proposed a new synonym request here: Request GCD synonym to Greatest Common Divisor

Original question:

I notice that the tag is defined on the main site as "greatest common divisor" and bears a wiki entry that says:

GCD generally refers to problems regarding greatest common divisors. This should not be used for Apple's Grand Central Dispatch (use for that).

The thing is, "GCD" is, with no offense to the 8th grade math students out there, is definitely best known in this forum as the abbreviation for Grand Central Dispatch. In fact if you look at the GCD tagged questions, most of them are Grand Central Dispatch related, despite the current admonishment of the gcd tag excerpt.

I would like to propose changing the gcd tag be redefined to be a synonym for Grand Central Dispatch. But I hesitate to just blithely edit the definition to be the precise opposite of the existing definition. Clearly I could just make the edit and see if it's approved, but that doesn't feel quite right.

What the correct protocol is here?

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The correct protocol is indeed to ask here.

However, I disagree with your proposed synonymization. "GCD" only means "Grand Central Dispatch" to Cocoa programmers. It means "Greatest Common Denominator" to anyone who ever had a math class.

Instead of synonymizing, questions which use when they mean should be edited.

  • 14
    I might even go so far as to say that gcd should be synonymized to greatest-common-divisor; there's no good reason to have such a short, potentially ambiguous tag. – Josh Caswell Jan 26 '13 at 8:24
  • +1 I agree with the problems of such a short, ambiguous tag, and therefore have proposed a synonym between gcd and greatest-common-divisor. – Robert Ryan Jan 28 '13 at 16:18
  • There are probably 2 useful programming questions about greatest common divisors...asked thousands of times by students. There are potentially thousands of useful Grand Central Dispatch questions. Why on earth do we need [gcd] to be greatest common divisor? (I have no skin in the Grand Central Dispatch game, not a tech I use) Maybe on Mathematics would this make sense. – user7116 Jan 28 '13 at 16:31
  • Another point to consider, @sixlettervariables, is what happens when the shiny new Android framework "Google's Cool Dongle" is released on the the same day as the "Guido Calculates Derivatives" module, and just a week after the much-anticipated "GNU Cloud Documents" library. Aficianados of each use "GCD", too; why should Grand Central Dispatch own the abbreviation on SO? Just avoid the whole mess and, since it'll be impossible to get rid of gcd altogether, use it for the meaning that's never going to change, and which everyone knows, regardless of platform. – Josh Caswell Jan 28 '13 at 18:54
  • @six: In other words, it's not so much that we need a [greatest-common-divisor]/[-denominator] tag, it's that it doesn't make sense to have a short, ambiguous tag referring to a topic with such limited recognition (and I am a user of Grand Central Dispatch). – Josh Caswell Jan 28 '13 at 18:57
  • @JoshCaswell: the same could have been said for WPF or ASP or PHP or whatever comes next...acronyms are part of the software ecosystem. Sometimes they clash, we deal with it when it arises. In this case the right answer is to not use the Mathematics definition (as that topic doesn't deserve a tag on SO) but to use the API definition. Users of SO agree in practice (Grand Central Dispatch >> Greatest Common Divisor), so why let this stand in the way? – user7116 Jan 28 '13 at 19:06

Voting on the synonym is not a good protocol here because only people with enough score in the tag can vote for or against the synonym. Talk about a biased sample! The proper protocol when two subcommunitites have a claim over a tag name is to discuss it on meta. Once the discussion has settled, moderators will implement its conclusion.

To the world at large, GCD means greatest common divisor. http://en.wikipedia.org/wiki/Greatest_common_divisor is the top hit for gcd on both Google (for me) and DuckDuckGo. On the other hand, if I add "programming" to the search, then Concurrency Programming Guide: Dispatch Queues (Google) and Grand Central Dispatch (GCD) on FreeBSD (DDG) win. Then again, I doubt most non-Objective-C programmers have even heard of Grand Central Dispatch, whereas greatest common divisor is part of a programmer's basic mathematical education.

So seems inappropriate (only makes sense to a small part of SO's audience), but on the basis of popularity I'm not convinced that is proper either. There is however another factor to consider: do people typically know what gcd in the arithmetic sense stands for? The abbreviation is almost always used, not the full expansion. That would be a reason to make a synonym.

  • +1 Because I have sufficient reputation on grand-central-dispatch, I didn't notice that the voting was not open to the broader audience. Good catch. I've altered by proposed action plan to just suggest that a moderator just go in and fix it. But it's silly to have an ambiguous tag for which the most common use (grand-central-dispatch) is considered a mistake by the broader "Meta" audience. If we can easily stop the frequent misused of a tag, that's a good thing. – Robert Ryan Jan 28 '13 at 15:34
  • By the way, I share your reservation about synonymizing gcd -> greatest-common-divisor, but I think it's better than not synonymizing it to anything and perpetuating the misuse of it simply because the number of grand-central-dispatch questions out-number the greatest-common-divisor questions. – Robert Ryan Jan 28 '13 at 15:37

I think asking here is the correct protocol.

Personally, I think math terms used as tags should probably be something of the form , but that hasn't been a standard up till now. I agree that gcd could be changed over (and synonymed), but someone would need to manually go through all the existing GCD questions and retag the "greatest common divisor" ones to whatever tag gets created for that.

Thinking about it more might work better for searches.

  • +1 on reply and edit. On retagging old questions, I understand your point (though there appear to be fewer greatest-common-divisor questions under GCD than there are Grand Central Dispatch answers that probably should be retagged if GCD definition is left unchanged). Ad re new math-gcd tag, maybe synonymize that with existing greatest-common-divisor tag. – Robert Ryan Jan 26 '13 at 6:42
  • Yeh, I thought about it more and edited something else in. – Lance Roberts Jan 26 '13 at 6:44

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