# Tag Info

4

These should be visible when viewing the site in a browser. If you mean using the mobile app, note that the mobile apps are no longer supported. However, you can tap on a comment and select an option to view the rendered mathjax. There is no such option for titles. If it's not visible on the mobile site with the blue theme, you can select full site with a ...

2

Take a look here: MathJax basic tutorial and quick reference MathJax is how it's all done. If you already know Latex you're $75\%$ of the way there.

3

As in Xander's answer, / can be used as a delimiter like ()[]|, by which I mean its adjusted by the commands \left, \right, \middle, and also \big, \Big, \bigg, and \Bigg. For instance, $A/B\big/C\Big/D\bigg/E\Bigg/$ gives $A/B\big/C\Big/D\bigg/E\Bigg/$. PS the slash slanting the other way can be achieved with $\Bigg\backslash$$\Bigg\backslash. Another way ... 5 Using the pmatrix environment (or bmatrix for square braces, but I find the round braces more aesthetically pleasing), the expression with a vinculum may be typeset with the code$$ \frac{% \begin{matrix}% A & B \\% C & D% \end{pmatrix} + 1% }{% \begin{pmatrix} D & E \\ F & G \end{pmatrix}% }. $$This is rendered as$$ \frac{%... 5 \frac{\left[\begin{array}{cc}A&B\\C&D\end{array}\right]+1}{\left[\begin{array}{cc}E&F\\G&H\end{array}\right]} $$\frac{\left[\begin{array}{cc}A&B\\C&D\end{array}\right]+1}{\left[\begin{array}{cc}E&F\\G&H\end{array}\right]}$$ Anything you can create in MathJax (as far as I know) you can put into a fraction using \frac{Top}{... 3 Use \sqrt[n]{m} to get the$n$th root of m:$\sqrt[n]{m}.$3 $$\sqrt{64}$$ produces $$\sqrt{64}$$ This is standard LaTeX syntax, see e.g. this page. It might be confusing since 'sqrt' is an abbreviation of 'square root', but it works nevertheless. 4 If you want real Fitch-style, you could use:$\def\fitch#1#2{\begin{array}{|l}#1 \\ \hline #2\end{array}}\def\fitch#1#2{\begin{array}{|l}#1 \\ \hline #2\end{array}}$This can be nested:$\fitch{¬B ∧ (A⇒B)}{ A⇒B \\ ¬B\\ \fitch{A}{ B \\ ¬B \\ ⊥ \\ } \\ ¬A }$Output is beautiful!$\fitch{¬B ∧ (A⇒B)}{ A⇒B \\ ¬B\\ \fitch{A}{ B \\ ¬...

13

You can't nest align environments but you can nest arrays (apparently, this requires $$...$$). Why would you bother? Because you can recreate the vertical line. Partial copy of the example of Luiz Martins: %PREAMBLE \newcommand{\FITCH}{\begin{array}{rlr}#1\end{array}} \newcommand{\FC}{\begin{array}{r}#1\end{array}} %FirstColumn \newcommand{\SC}{\... 24 Another option is to use the align environment \begin{align*}...\end{align*}, rather than the array environment. This environment has more flexibility with spacing, which is useful if you don't want your output to look like a table (although this doesn't seem relevant to your example). The align environment gives an essentially identical output to array here:... 19%PREAMBLE \newcommand{\fitch}{\begin{array}{rlr}#1\end{array}} \newcommand{\fcol}{\begin{array}{r}#1\end{array}} %FirstColumn \newcommand{\scol}{\begin{array}{l}#1\end{array}} %SecondColumn \newcommand{\tcol}{\begin{array}{r}#1\end{array}} %ThirdColumn \newcommand{\subcol}{\begin{array}{|l}#1\end{array}} %SubProofColumn \newcommand{\subproof}{...

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