Latex tabularx issue with spacing

So just trying to edit a table someone had done in tabularx as I liked the style however I have no idea what I'm doing really and as such I've come up against a problem. There is a big space after the entry 'setup', in the below code and I would like it all to be nice and symmetrical the space makes it very asymmetrical. Is there a way to remove this space?

\documentclass{article}
\usepackage{array}
\usepackage{booktabs}
\usepackage{ragged2e}
\usepackage{tabularx}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\newcolumntype{Y}{>{\RaggedRight\arraybackslash}X}

\begin{document}
\noindent
\edef\TabularRowHeight{\the\dimexpr-\arraystretch\baselineskip}

\begin{tabularx}{\textwidth}{YY}
\toprule
Alice  &  Bob \\
\midrule
\emph{Setup}\\
\cmidrule(lr){1-1}
Alice \& Bob select a prime $p$ and a generator $g$ for the finite field $\mathbb{F}_p$
&\\

&\emph{Private Computation}\\
\cmidrule(lr){2-2}
&  Bob randomly selects $b \in \mathbb{F}_p$ and then computes the following:

$B \equiv g^b \mod p$ once computed Bob sends Alice $B$

\\[\TabularRowHeight] & \\

& \emph{Key Computation}\\
\cmidrule(lr){2-2}
& Bob who now has $A$, calculates the following:$A^b \equiv (g^a)^b \equiv g^{ab} \mod p$

\\

\emph{Private Computation}\\
\cmidrule(lr){1-1}
Alice randomly selects $a \in \mathbb{F}_p$ and then computes the following:

$A \equiv g^a \mod p$ once computed Alice sends Bob $A$ & \\ \pagebreak

\emph{Key Computation}\\
\cmidrule(lr){1-1}
Alice who now has $B$, calculates the  following:$B^a \equiv (g^b)^a \equiv g^{ab} \mod p$ & \\

\bottomrule

\end{tabularx}
\end{document}


Picture of current output

Output I'd like to achieve

• Can you post a screenshot of the result? I don't get any unusual space other than the empty cells with are explicitly added in the code. Do you maybe want to remove these? Sep 6, 2019 at 15:39
• Perhaps I do want to remove these, I am working out what does what of a similar table not familiar with using this package at all. Will add a picture for you ! Sep 6, 2019 at 15:44

I don't think removing the alternating layout from the table you showed makes a lot of sense, but here is a try

\documentclass{article}
\usepackage{array}
\usepackage{booktabs}
\usepackage{ragged2e}
\usepackage{tabularx}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\newcolumntype{Y}{>{\RaggedRight\arraybackslash}X}

\begin{document}
\emph{Setup}: Alice \& Bob select a prime $p$ and a generator $g$ for the finite field $\mathbb{F}_p$
\begin{tabularx}{\textwidth}{@{}YY@{}}
\toprule
Alice  &  Bob \\
\midrule
%    \cmidrule(r){1-1}\cmidrule(l){2-2}
Alice randomly selects $a \in \mathbb{F}_p$ and then computes the following:

$A \equiv g^a \mod p$ once computed Alice sends Bob $A$& Bob randomly selects $b \in \mathbb{F}_p$ and then computes the following:

$B \equiv g^b \mod p$ once computed Bob sends Alice $B$\\\addlinespace[1.2em]

%    \cmidrule(r){1-1}\cmidrule(l){2-2}
Alice who now has $B$, calculates the  following:$B^a \equiv (g^b)^a \equiv g^{ab} \mod p$  & Bob who now has $A$, calculates the following:$A^b \equiv (g^a)^b \equiv g^{ab} \mod p$
\\
\bottomrule

\end{tabularx}
\end{document}


Instead I would prefer a 3-column layout:

\documentclass{article}
\usepackage{array}
\usepackage{booktabs}
\usepackage{ragged2e}
\usepackage{tabularx}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\newcolumntype{Y}{>{\RaggedRight\arraybackslash}X}

\begin{document}
\emph{Setup}: Alice \& Bob select a prime $p$ and a generator $g$ for the finite field $\mathbb{F}_p$
\begin{tabularx}{\textwidth}{@{}>{\RaggedRight\arraybackslash}p{2.2cm}YY@{}}
\toprule
& Alice  &  Bob \\
\midrule
\emph{Private \linebreak Computation} & %
Alice randomly selects $a \in \mathbb{F}_p$ and then computes the following:

$A \equiv g^a \mod p$ once computed Alice sends Bob $A$& Bob randomly selects $b \in \mathbb{F}_p$ and then computes the following:

$B \equiv g^b \mod p$ once computed Bob sends Alice $B$\\\addlinespace
\emph{Key \linebreak Computation} & Alice who now has $B$, calculates the  following:$B^a \equiv (g^b)^a \equiv g^{ab} \mod p$  & Bob who now has $A$, calculates the following:$A^b \equiv (g^a)^b \equiv g^{ab} \mod p$
\\
\bottomrule

\end{tabularx}
\end{document}


• Thanks just wondering is it possible to have the subheadings for the bob column as well? And to have a horizontal line above the setup? Just looking through the code now trying to work out what's happening. :) Sep 6, 2019 at 16:01
• @Dead_Ling0 Try with \emph{Private Computation}:&\emph{Private Computation}:\\ \addlinespace, but having redundant information in your table will decrease the information-to-noise ratio dramatically Sep 6, 2019 at 16:04
• Thank you kindly you've been most helpful, will try to understand what you've done any resources where I can learn about tableux the latex wiki wasn't very helpful. Sep 6, 2019 at 16:10
• @Dead_Ling0 I can recommend dickimaw-books.com/latex/novices/html/index.html for latex beginners. From your question, I think your problem is not really related to tabularx, but rather about general mechanics of tabular in latex (tabularx is just a special case of a tabular). A short summary: www1.maths.leeds.ac.uk/LaTeX/TableHelp1.pdf Sep 6, 2019 at 16:20