Rules of Inference aligning on latex document

Question

Hi I'm trying to write a neat step by step description of rules of inference just like the picture below

It seems like there are 3 columns and on each column it is center aligned.

Is this form just using tables without lines?? If there is anyone who has experience writing a document on propositional logic pls give out some tips. Thanks

Answer 1

A solution provided by @Werner is reproduced below -- https://tex.stackexchange.com/a/410766/197451

Two proof environments are provided:

proofA

and

proofB

The first uses a regular tabular, the second uses a tabularx that allows for justified paragraph text.

MWE

\documentclass{article}

\usepackage{tabularx}

\newcounter{proofstep}
\newcommand{\step}{}
\newenvironment{proofA}
  {\par
   \setcounter{proofstep}{0}%
   \renewcommand{\step}{\refstepcounter{proofstep}\theproofstep. &}%
   \noindent
   \begin{tabular}{ @{} r c l @{}}}
  {\end{tabular}}
\newenvironment{proofB}
  {\par
   \setcounter{proofstep}{0}%
   \renewcommand{\step}{\refstepcounter{proofstep}\theproofstep. &}%
   \noindent
   \tabularx{\textwidth}{ @{} r c X @{} }}
  {\endtabularx}

\begin{document}

\noindent
\begin{tabular}{ @{} r c l @{} }
  1. & some math & Justification. \\
  2. & some math & Justification.
\end{tabular}

\begin{proofA}
  \step some math & Justification. \\
  \step some math & Justification.
\end{proofA}

\begin{proofB}
  \step some math & This is just another sentence that will span at least two 
   lines. Well, now it will, for sure! \\
  \step some math & Justification.
\end{proofB}

\end{document}

The header row can be added by modifying the code for the tabular environment as follows

\begin{tabular}{ @{} r c l @{} }
     & \textbf{Step} & \textbf{Reason}\\
  1. & some math     & Justification. \\
  2. & some math     & Justification.
\end{tabular}