\documentclass[a4paper,12pt,twoside]{book}
\usepackage{etex}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath,amssymb,amscd,amsbsy,array,color,epsfig}
\usepackage{fancyhdr,framed,latexsym,multicol,pstricks,slashed,xcolor}
\usepackage{picture}
\usepackage{indentfirst}
\usepackage{enumitem}
\begin{document}
\begin{proof}
\begin{table}[!ht]
\centering
\begin{tabular}{|c|c||c|c|c||c|c|}
\hline
$P$ & $Q$ & $P \Rightarrow Q$ & $\neg P$ & $\neg Q$ & $(\neg Q) \Rightarrow (\neg P)$ & $Q \Rightarrow P$ \\
\hline
$T$ & $T$ & $T$ & $F$ & $F$ & $T$ & $T$ \\
\hline
$T$ & $F$ & $F$ & $F$ & $T$ & $F$ & $T$ \\
\hline
$F$ & $T$ & $T$ & $T$ & $F$& $T$ & $F$ \\
\hline
$F$ & $F$ & $T$ & $T$ & $T$ & $T$ & $T$ \\
\hline
\end{tabular}
\caption{\emph{Truth Table for $P \Rightarrow Q$, $(\neg Q) \Rightarrow (\neg P),$ and $Q \Rightarrow P.$}}
\end{table}
\end{proof}
\end{document}
Hopefully I have given enough information in the MWE, because in my original I have a preamble, a table of contents, a chapter 0 (from which the table comes), and an analysis file which has the previous as inputs. So, I might have left something out that is needed from the MWE for it to compile.
But when I compile I get the following error at the beginning of the table:
Not in outer par mode \begin{table}[!ht]
Undefined control sequence \begin{table}[!ht]
Missing number, treated as zero \begin{table}[!ht]
Thanks.
Best Answer
An attempt:
Some suggestions:
Do you really need float
table
in the proof? An unnumbered version (only tabular) is less problematic.If you use
array
insted oftabular
, all your dollars inside it are unneeded.There were some suggestions about packages in comments.