# With all other variables held constant, are tags sufficient to contextualize a question?

Recently, I made a comment here that, for this particular question, given the tags (the tags were there before the edit occurred), it is clear what the context should be. However, one of the people responding to my comment disagreed.

As another example, suppose someone asked me how to show $\lim\limits_{x \to 3}x = 3$.

If I saw as the only tag for this question, I probably wouldn't talk about $\delta$-$\epsilon$ or even plugging in the value for $x$ due to continuity (unless they mention otherwise that they've learned about continuity). Instead, I would focus on graphical intuition.

If I saw as one of the tags (N.B.: not the only tag), I would mention continuity and the theorem that you can plug in values due to polynomials being continuous.

If I saw as one of the tags, I would probably mention doing a $\delta$-$\epsilon$ proof (unless otherwise desired).

What says the community? If a question is asked perfectly well, are tags enough to contextualize a question?

The reason why I am concerned about this in the first place is that - in my opinion - we can't expect each user of this site to know their topics on which they have questions in the utmost generality, and if they've asked their question well, with appropriate tags, in the majority of cases, that should be enough to understand the question (and to not mark it to be closed for lack of context).

• For what it's worth, I just saw a question on MO about high school algebra homework, with the tag, central-simple-algebras. – Gerry Myerson Jun 17 '16 at 0:02
• I think $\lim$ barely makes sense without knowledge of $\epsilon-\delta$. Also, I really don't believe there is a "calculus vs real analysis" dichotomy, I would say "real analysis" is a rather sophisticated branch of calculus, which however doesn't mean there should be any less rigour in calculus than in real analysis. – Vim Jun 17 '16 at 11:41
• "With all other variables held constant [...]". With this phrasing, it is easy to guess which Stack Exchange meta site we are on :) – Therkel Jun 18 '16 at 14:03
• $\text{lim}$ can be defined purely based on topology, with no use of epsilons or deltas... – Nick Alger Jun 19 '16 at 19:35

I can imagine a question asking for $\varepsilon\!-\!\delta$ proof of a limit posting under any of the tags you mention (even if inappropriately), or a question wanting graphical intuition showing up under . Plus, it's always possible that the author was only introduced to some less common formulation of limits, but isn't aware of it. In any of these cases, we get a clearer picture of the question by using comments to ask for the particular definitions in play. The tags can help guide comments to more specific suggestions of, "I assume you mean ____. Is that what you're after?"