# How do you tag without brackets? In particular, how do you tag boxes?

How would you tag boxes without brackets after completing a proof? For example, I needed to prove that $$\forall m, n \in \mathbb{N}\cup \{0\}, \ n^{2m + 1} \equiv -1 \pmod {n + 1}$$ I proved this by showing that $$n^{2m + 1} + 1 = n^{2m + 1} - (-1) = n^{2m + 1} - (-1)^{2m + 1}$$ And since $$a^k - b^k = (a - b)\sum_{i = 1}^k a^{k - i}b^{i - 1}$$ then this meant $$n + 1 \mid n^{2m + 1} + 1$$ or $$n^{2m + 1} \equiv -1 \pmod {n + 1}$$ In the event that I want to draft up a proof using LATEX, how would I tag a box $\Box$ to show that I have demonstrated the proof without it having brackets like $(\Box)$? Namely, if I had a Statement $A$ then I don’t want it looking like $$\text{Statement A}\tag{\Box}$$ and if I use \quad and/or \qquad then it looks like $$\text{Statement A}\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad \ \ \ \ \Box$$ Thank you in advance.

• @MartinSleziak thanks for the edit :) – Mr Pie Jan 16 '18 at 6:54

EDIT: I agree with what mixedmath says in their answer that this is not a reasonable thing to do in order to mark the end of a proof. I read your question simply as a TeX-nical (or MathJax-nical) question: "How do I mark equation with $\Box$ rather than $(\Box)$ on the right?"

Probably the intended question is related to possibilities how to mark end of proof (in a way similar to \qed in LaTeX), which is question related to style of writing and MathJax. (And which means that I have misunderstood your question.) Probably you might have a look at past discussion here: \qed for MathJax here on stackexchange.

If you do not net MathJax markup in the tag you can do this simply using \tag*. Compare the following two equations: $$a^2+b^2=c^2 \tag{1}$$ $$a^2+b^2=c^2 \tag{1}$$ and $$a^2+b^2=c^2 \tag*{1}$$ $$a^2+b^2=c^2 \tag*{1}$$

It is slightly complicated if you want some mathematical formula as a part of the tag, see also here: I can't put a Greek letter into \tag{…}

You can do this $$a^2+b^2=c^2 \tag{\Box}$$ $$a^2+b^2=c^2 \tag{\Box}$$ and also this $$a^2+b^2=c^2 \tag*{\Box}$$ $$a^2+b^2=c^2 \tag*{\Box}.$$

I would typically expect you to include a box inline, such as this. $\square$

An indication that you are trying to do something in a way that isn't how it is designed is that you are trying to use tag to produce something other than a tag or label.

If you really want to shove a square to the far right, I only know how to do this (with mathjax) in a multline environment, as below.

$$\begin{multline} \shoveright \square \end{multline}$$

But I would suggest that you never do this.

• Interestingly, using \tag* is one of the suggested solutions in the previous discussion about this. I will leave to others to judge whether this is good style or not. (Personally I consider the advice from your answer very reasonable.) – Martin Sleziak Jan 16 '18 at 7:15

I mostly separate sections on this site with

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

which usually comes out matching the width of my answer window. My idea is that people can't read this site as carefully as a book they are holding in their hands, something that crosses the window gives a more reliable notice that something different is starting. if you want to say QED before that, fine.

• I will add that it is also possible to use simply <hr> or ---. (In which case you do not have to worry about the length, the SE software does that for you.) For other possibilities, see the section on horizontal rules in editing help. – Martin Sleziak Jan 17 '18 at 6:29
• It might match the width of your answer window, but other people might be viewing in a phone browser or with different fonts installed on their computers. --- is much more consistent. – Peter Taylor Jan 18 '18 at 14:58