fractions -> rational-numbers and gcd -> divisibility

I have mentioned some relevant links here.

(Since quid already mentioned gcd, I have added the other one that was discussed.)

@quid is right that this can't probably be resolved without moderator intervention

1) Tag synonyms can be cancelled only by mods. (Of course, the consensus of the community plays an important rule by the decision whether to remove the synonym.)

2) There is about 10 or 15 users who have big enough score in (greatest-common-divisor) to suggest a synonym and vote for/against a synonym. (IIRC you need score at least +5 in the tag.) That's simply not enough to expect realistically that community will create the synonyms for greatest-common-divisor.

BTW thanks to Arthur for making highest-common-factor a synonym of greatest-common-divisor: meta.math.stackexchange.com/questions/20777/…

@MartinSleziak Spent a bit of time looking into this. One problem I see with removing the gcd ⇒ divisibility synonym is that I didn't act all that well when I created it. By this I mean that I merged the two tags, meaning that all divisibility tagged questions would have to be looked at to see if they are really about divisibility or gcd (or both) and retag as appropriate.

The fractions ⇒ rational-numbers synonym shouldn't be as problematic, as I'm pretty sure it's just a straight synonym, meaning that older questions weren't silently retagged when the synonym was put in. It would mean that newer questions tagged rational-numbers would have to be looked at, but this should be more manageable.

@ArthurFischer Personally I think that it is ok to consider gcd as subtag of divisibility. So I'd say that if they were merged, those question will have a correct tag, but maybe gcd will be missing.

@ArthurFischer I do not see why this would create a problem for removing this synonym right now.

I wonder how many questions tagged (gcd) were there before the merge.

@MartinSleziak llooking at the old meta post hardly any it is to be assumed.

@quid I do not know the details, but from some threads I've seen on meta.SE it seems that if the tags have been merged, then after the removing the synonym all of them will be tagged (divisibility). If they were only synonimyzed, not merged, then we would get bunch of questions tagged (gcd) and bunch of questions tagged (divisibility).

@quid Just a potential additional workload. Although it does appear to be a more-or-less lateral move from the current situation.

For example, the answer in "Need a rollback/undo for tag synonym merging" seems to suggest this behavior.

I am not sure whether this was what Arthur was getting at, when he mentioned that the tags were merged.

@MartinSleziak You mean you won't go through the nearly 1800 divisibility questions to find the rare gcd nugget!?

Yes, but this is irrelevant in my opinion. Either one thinks the questions are properly tagged with divisibility, in which case there is no problem with them being tagged divisibility even if an independent tag gcd exists. Or one thinks they are not, in which case it is all the more more urgent to remove the synonym.

The above is even more true as the tag greatest common divisor exists.

@ArthurFischer You'll probably need a sarcasm sign.

I really consider the current situations as impossible.

I kind of wish the gcd-related tags would just disappear. Oy veh!

Well... let's see what happens...

(famous last words, I know.)

I mean, even if we agree that after removing the tag synonym there will be many questions which do not have (gcd) tag and they should have it, removing the synonym is the first step. (At least if the consensus seems to be that the two tags should be separate.)

@MartinSleziak yes this! And if the opinion changes we can just recreate the synonym. Really nothing much is lost with removing the synonym.

And even if it means that then we have some incorrectly tagged questions (I'd rather say less than optimally tagged), it's not like we do not have many of them already.

Okay, those two synonyms have been removed.

There are even whole tags usage of which is rather unclear.

The gcd tag no longer exists (as expected).

May it rest in pieces.

The fractions situation seems a bit more curious.

@ArthurFischer Thanks Arthur. Am I correct in guessing that eventually you'll make a post on meta explaining what happened? (So that the rest of the community has some king of update.)

@MartinSleziak Yeah, I'll write something up. Somewhere.

@ArthurFischer Sometime.

@ArthurFischer Thanks! while you are at it could you please cancel the lcm and least common mulitpple proposed synonyms for divisibility .

@AsafKaragila Somehow.

@quid Sure thing.

@ArthurFischer Should we blame caching? I the site still shows me 1190 questions tagged (fractions) and 1190 questions tagged (rational-numbers).

@ArthurFischer Somewhy, and somewho too?

@MartinSleziak I'm hoping it's caching. It's very strange right now.

@AsafKaragila Yes, I am an instance of somewho, and the reason is an instance of somewhy. Logic is fun.

You guys mean the gcd tag? Shows up empty here.

@ArthurFischer Not as fun as finding out that there are a bunch of new technical lemmas with silly proofs that you need to write, though! :-D

@MartinSleziak 701 times fractions, and 513 times rational-numbers

So it was probably caching. I see the same thing now. 24 questions having both of them‌​.