Centering in tabular does not work

Question

The following is a minimal example of a table I am defining. The first row ($v_1$ and $v_2$) are not centered, but the subsequent rows are. What am I doing wrong?

\documentclass{article}
\usepackage{array}

\begin{document}
    \begin{tabular}{| m{1cm} | m{1cm} |} 
        \multicolumn{2}{c}{\footnotesize Subgraph Matches} \\ \hline
        $v_{1}$ & $v_{2}$ \\ \hline
        \{005\} & \{006\} \\ \hline
        \{007\} & \{008\} \\ \hline
    \end{tabular}
\end{document}

Answer 1

Centering in tabular is done with the c column type. The m column type is used for vertical centering, not horizontal centering which is what this table needs:

However, you should really consider the booktabs package which produces more professional looking tables:

Code:

\documentclass{article}
\usepackage{array}
\usepackage{booktabs}

\begin{document}
    \begin{tabular}{| c | c |} 
        \multicolumn{2}{c}{\footnotesize Subgraph Matches} \\ \hline
        $v_{1}$ & $v_{2}$ \\ \hline
        \{005\} & \{006\} \\ \hline
        \{007\} & \{008\} \\ \hline
    \end{tabular}

    \bigskip\bigskip
    \begin{tabular}{ c  c } 
        \multicolumn{2}{c}{\footnotesize Subgraph Matches} \\ \toprule
        $v_{1}$ & $v_{2}$ \\ \cmidrule(lr){1-2}
        \{005\} & \{006\} \\ %\cmidrule(lr){1-2}
        \{007\} & \{008\} \\ \bottomrule
    \end{tabular}
\end{document}