# Is the tag [venn-diagram] necessary?

Recently the tag was created, with a tag wiki, and currently 20 questions tagged (although 19 of which were tagged by the creator shortly after).

## Do we really need this tag?

On the one hand, it is going to be helpful in filtering questions which are specifically about Venn diagrams, for better and for worse. And while most of these are questions about [very elementary] set theory, some of them are not (e.g. "can you draw a Venn diagram in such and such way").

On the other hand, searching for questions about Venn diagrams is fairly easy, as they all pretty much contain the phrase "Venn diagram". And the striking majority of these are already tagged under or .

So is this tag worth saving?

• My default stance has always been that if there is a debate and no good arguments, then the tag is probably redundant. But that's me and my very conservative tag view, and I'm sure that there are people opposite of me. But I wanted to poll the opinion of the rest of the community.
– Asaf Karagila Mod
Dec 20, 2017 at 11:10
• From me +1 with intended meaning of the upvote: "It is good that somebody brought this up on meta." (I hope my reading of the question is correct and voting on the question is not intended as voting for/against removal of the tag.) Dec 20, 2017 at 13:35
• Yes, I tried to raise this as an impartial topic for debate, not as a proposal.
– Asaf Karagila Mod
Dec 20, 2017 at 13:45
• IMO anything that has venn-diagram and probability should just have probability. I don't consider Venn diagrams in probability to be significant enough to warrant a new tag specifically for probability questions; they are merely a tool to visualize a very specific subset of probability problems. Dec 21, 2017 at 15:23
• @StefanMesken Why not making your last two comments into an answer. In this way we could get a feedback from users on your suggestion to remove the tag (both in the form of further comments and also in the form of up/downvotes on the answer). Moreover, the suggestion will be more visible than here in comments. Dec 22, 2017 at 8:44
• It would seem to be subsumed by combinatorics or set theory. I don't see a need for it. Dec 23, 2017 at 18:40
• @Martin: What do you make of all this?
– Asaf Karagila Mod
Dec 27, 2017 at 7:09
• @AsafKaragila The answer suggesting removal of the tag is currently at +5 - that is higher number of votes than tag-related suggestions usually get. (Not everybody is interesting in these issues.) So maybe it would be possible to start removing the tag based on the discussion so far. (And if somebody still objects to the removal, they can post their objection as an answer here.) Dec 27, 2017 at 7:15
• I will add that your question is less that 14 days old so it is still selected for community bulletin. So it it still possible that somebody who might have something to say about this notices this discussion. Dec 27, 2017 at 7:15
• @Martin: Well, okay. I guess we can wait a bit longer.
– Asaf Karagila Mod
Dec 27, 2017 at 10:31
• @Martin: It seems the user who created the tag started to de-tag...
– Asaf Karagila Mod
Dec 28, 2017 at 14:13
• My two cents: Hoffman-Kunze tag is not needed, Venn diagram tag is. I am not convinced every Venn diagram question will necessarily have the term in it. Most prime numbers questions have the words "prime" and "number" in them, but no one questions the usefulness of that tag. Jan 3, 2018 at 6:20
• @RobertSoupe It might be useful to expand this to an answer so that can we can get feedback from other users. (In comments or at least through voting. So far it seemed that most of the reactions here were for the removal of the tag.) It might be also useful to clarify what is the intended usage of the tag. Jan 3, 2018 at 12:55
• @MartinSleziak Alright, only because you asked. Jan 4, 2018 at 16:34

In my experience, both the range and frequency of questions that deal with Venn diagrams at their heart (i.e. don't just use them as a simple tool to answer a question of independent interest) is very limited. And since question that deal with the theory of Venn diagrams itself are easy to find, like Asaf already said in an earlier comment, it seems to me that this tag is in fact of marginal value and should probably be dropped.

The same reasoning applies to other tools -- like Łoś' Theorem or the Compactness Theorem. Both are frequently used but rarely themselves the object of interest in any given post. And even in those rare instances that they are, there is no shortage of other relevant tags that will attract users with the appropriate background to answer those questions.

• You should probably clarify that compactness means the one in mathematical logic, which to some extent does fall under the compactness if we are being strict.
– Asaf Karagila Mod
Dec 22, 2017 at 11:03

My two cents: the Hoffman-Kunze tag is not needed, the Venn diagram tag is. The reason I bring up Hoffman-Kunze is that a similar question about that tag was in "Hot Meta Posts."

I am not convinced every Venn diagram question will necessarily have the term in it. Most prime numbers questions have the words "prime" and "number" in them, or at least "prime," but no one questions the usefulness of that tag.

The availability of the right tags benefits not just those who asking questions but also those who edit questions. I'm pretty sure I've added the prime numbers tag to at least one question.

I don't think I've ever added the Venn diagram tag to any question, but I can see myself doing so. Adding a tag for a specific textbook? Probably not, not even if it was the Liber Abaci.

• Yes, but searching for the word "prime" is different than searching for the word "Venn". Not to mention that prime numbers are a topic of interest, whereas Venn diagrams are almost entirely just a way of proving something. If anything, a more apt comparison would to the [limits] and [limits-without-lhospital] tags. But even there, there was an actual necessity, whereas here, I don't feel there is one (and I am not the only one, as it seems).
– Asaf Karagila Mod
Jan 5, 2018 at 1:06
• Also the comparison to the Hoffman and Kunze is different, because that one is about a specific textbook. That's a topic that was brought up before, and was voted in a similar way, there shouldn't be tags related to specific books. Here we are talking about tags related to a general objects in mathematics (more similar to prime numbers, as you suggest).
– Asaf Karagila Mod
Jan 5, 2018 at 1:08
• So to reiterate my point in a summarized way. Can you think of 50 different questions about Venn diagrams? I can't. And unlike limits, I don't feel that as a technical matter there is a need for a separate tag for them.
– Asaf Karagila Mod
Jan 5, 2018 at 1:09
• I can easily think of fifty different questions about Venn diagrams. I'm guessing you meant fifty such questions that won't get closed on here. For that, just five questions would be a challenge. Jan 5, 2018 at 6:01
• @RobertSoupe Probably this depends a bit on what you understand by a question about Venn diagrams. I would consider this a question about Venn diagrams: Venn diagram with rectangles for $n > 3$. But for example, here Venn diagram is just a tool: What portion of work is done alone by students of a class?. So it is not that clear whether this is question about Venn diagrams and whether it belongs under the tag or not. (That is, assuming that the tag stays.) Jan 5, 2018 at 7:05