Alignment problems with table using tabularx

Question

I have a problem with a table which I am using for a publication. The code is as follows:

\begin{table}[htbp]
    \centering
    \captionof{table}{Summary}
%    \begin{tabularx}{0.5\textwidth}{| c | X | X |}
\begin{tabularx}{0.5\textwidth}{| c |>{\centering\arraybackslash}X | >{\centering\arraybackslash}X |}
      \hline
        Reference     & Focus     & Relevance to Model     \\ \hline
        \rule{0pt}{4ex} [4]         & \tabitem Model\newline\tabitem  peformance benchmarks        & Relevant         \\ \hline
         \rule{0pt}{4ex} [5]         & \tabitem Deployment Algorithms \newline \tabitem Analysis of algorithmic efficiency        & Relevant         \\ \hline
    \end{tabularx}
\end{table}

Now this results in the output included in the attached image. I need a center alignment for the heading row, but for the remaining rows, I would like to choose a center alignment for the first column, and a left alignment for the rest. Also, it is evident from the image that the bullets are not aligned properly. I guess this has something to do with the \tabitem. I tried replacing it with itemize but that just made things worse. So I would really appreciate a workaround to this problem.

Answer 1

The OP left much undefined by providing snippets of code, rather than an MWE, so I improvised.

I redefined your \tabitem to exit vertical mode, and I placed the space following the bullet within the \llap itself. I also made the list raggedright. I added extra column space before the 2nd column, to offset the \llaped bullet.

Finally, I reduced the \rule height from 4ex to 2.5ex to reduce the overhead space in the row entries, and removed the space between the rule and the [4], [5] entries, to achieve true horizontal centering.

\documentclass{article}
\usepackage{caption,tabularx}
\newcommand{\tabitem}{\leavevmode\llap{\textbullet~}\raggedright}
\begin{document}
\begin{table}[htbp]
    \centering
    \captionof{table}{Summary}
    \begin{tabularx}{0.8\textwidth}{| c | @{\hspace{3ex}}X | X |}
      \hline
        Reference     & \hfil Focus\hfil     & \hfil Relevance to Model\hfil     \\ \hline
        \rule{0pt}{2.5ex}[4]         & \tabitem Model\newline\tabitem  peformance benchmarks        & Relevant         \\ \hline
         \rule{0pt}{2.5ex}[5]         & \tabitem Deployment Algorithms \newline \tabitem Analysis of algorithmic efficiency        & Relevant \\ \hline
    \end{tabularx}
\end{table}
\end{document}

In the comments, David suggests you use an actual list environment (like itemize). Below, I show how that might be done, though adjustments also have to be made here to allow for the extra space that such environments introduce.

\documentclass{article}
\usepackage{caption,tabularx}
\begin{document}
\begin{table}[htbp]
    \centering
    \captionof{table}{Summary}
    \begin{tabularx}{0.8\textwidth}{| c | X | X |}
      \hline
        Reference     & \hfil Focus\hfil     & \hfil Relevance to Model\hfil     \\ \hline
        \rule{0pt}{4ex}[4]         & 
\vspace{-17pt}\raggedright
\begin{itemize}\item Model\item  peformance benchmarks\end{itemize}        
& Relevant         \\ \hline
         \rule{0pt}{4ex}[5]         & 
\vspace{-17pt}\raggedright
\begin{itemize}\item Deployment Algorithms \item Analysis of algorithmic efficiency\end{itemize}
& Relevant \\ \hline
    \end{tabularx}
\end{table}
\end{document}