# (proof-explanation) tag

I have noticed among the new tags. Although the name of the tag sounds reasonable and it seems to be self-explanatory, I am not sure whether we need a new meta-tag. So I wanted to ask on meta about the opinion of other users on this tag.

At the moment the tag has 10 questions, although it seems that in most cases the tag was added by the tag creator.

• I have also pinged the user who created this tag and let them know about this discussion on meta. So perhaps we will get also some explanation from them. – Martin Sleziak Jan 14 '14 at 19:44
• mezhang's answer received quite a lot upvotes, so I have accepted it. – Martin Sleziak Jan 24 '14 at 11:43

## 2 Answers

I often run into situations where I'm reading a book and get stuck at certain sentence. These are places where authors assume the implication follows obviously, but due to certain reasons (lack of familiarity with the subject, with previous chapters etc.), I fail to see it. All I need is 2-3 sentences more to explain this particular step. These type of a questions usually can be answered within a few lines. In other words, these are small bottlenecks I run into during learning.

Usually I bring these questions to my professors, but since they occur very often, and they usually require getting into the technicality of reading the whole proof, getting used to the notation etc, I don't always get a reply.

That's why I created the tag. I have seen many questions like these before, but at time of creation I could only tag a few, starting with my own.

I don't think it is similar to proof-verification. In proof-verificatio the asker knows the idea of the proof but lack execution or need verification. But here the asker need explanation of an indea which he failed to see through.

Regarding what Grigory M and Martin Sleziak said, at least my purpose for this tag is not to seek intuition behind proofs, nor am I seeking explanation of the whole proof, but rather a specific line about a specific implication which needs only very short answer.

• Thanks for letting us know your reasons for creating the tag. – Martin Sleziak Jan 15 '14 at 11:53
• Thank you for explaining. Still, I believe that's not how tags should be used: as you write in the answer, this tag is about how you personally ran into this problem. But tags on Math.SE should be about the actual contents of the question. – Grigory M Jan 15 '14 at 16:59
• Maybe my explanation is not very clear... Come to think of it, this reminds me of twitter hash-tags, somehow — Math.SE tag are not at all like twitter hash-tags, but it's not immediately clear from help etc. – Grigory M Jan 15 '14 at 17:03

Some meta tags are allowed (or at least tolerated) on Math.SE, but I don't understand (intended) semantics of this one:

• if OP does understand all steps in the proof, but wants to ask something about behind it — there is corresp. tag already;
• if OP doesn't understand some step in the proof — like this proof uses that any frumious bandersnatch is vorpal, but why is that true? — than this question should, IMO, have exactly the same tags as studying bandersnatches I came to the conjecture that every frumious bandersnatch is vorpal — is it true? how to prove it?.

(More generally, tags should be about the question, it's mathematical contents — and not about the asker, about circumstances where he seen the question etc.)

• Since the user who created this tag have not said their thoughts yet I will say how I understand this tag (based on the name and the question tagged with it so far). It is mostly when the OP does not understand some step in the proof. Not in all cases the student is able to exactly pinpoint something in the form: The only thing I do not understand is why every frumious bandersnatch is vorpal. Quite often you see the questions like: I understand the beginning of the proof. But how does the author get from this line to this line? (Once we know that it is a vorpal, the rest is clear to me.) – Martin Sleziak Jan 15 '14 at 6:07
• Also to some extent it is similar to the (proof-verification). In both cases the question is not How to prove this thing? It is: I have a question about one particular proof of this thing. (In one case it is the OP's own proof, in another it is proof from some source.) – Martin Sleziak Jan 15 '14 at 6:09
• I wrote my thoughts @MartinSleziak – mez Jan 15 '14 at 11:49
• @Martin As a side note, (proof-verification) may be considered a meta-tag, but its semantics is clear to me: while most questions ask to prove / find something ('ask some question'), these questions already give an answer, which should be verified — (unlike in my second point) question 'I have a proof that every frumious bandersnatch is vorpal, please check it' is not at all equivalent to '(...). How to prove it?', it requires different kind of work from the answerer. – Grigory M Jan 15 '14 at 17:10
• ...and frankly, I don't like this kind of questions — so at least for me (proof-verification) is a very useful tag: I've added it to the ignore list. – Grigory M Jan 15 '14 at 17:12