Math Mode – How to Properly Resize an Array

math-mode

At the moment my latex code looks like this but I get two errors saying Missing $ inserted. } . I have tried a lot to fix it but nothing helps. I am not sure if I am using a symbol that is messing with math mode or what's wrong. 

\item \resizebox{\textwidth}{!}{\[\displaystyle
    \begin{array}{lp{2mm}cll} 
    (\A \oplus \B) \oplus \B & & \equiv & \big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\oplus\B & \text{(Def of $\oplus$)}        \\[2mm]
                             & & \equiv & \Big(\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\wedge\neg\B\Big)\vee\Big(\neg\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\wedge\B\Big)& \text{(Def of $\oplus$)}        \\[2mm]
                             & & \equiv & \Big(\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\wedge\neg\B\Big)\vee\Big(\big((\neg\A\vee\B)\wedge(\A\vee\neg\B)\big)\wedge\B\Big)& \text{(De Morgan Laws Double Negation)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\big((\neg\A\vee\B)\wedge\B\wedge(\A\vee\neg\B)\big)& \text{(Associativity Commutativity)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\Big((\neg\A\vee\B)\wedge\big((\B\wedge\A)\vee(\B\wedge\neg\B)\big)\Big)& \text{(Distributivity)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\Big((\neg\A\vee\B)\wedge\big((\B\wedge\A)\vee\false\big)\Big)& \text{(Negation)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\big((\neg\A\vee\B)\wedge\B\wedge\A\big) & \text{(Neutrality Associativity)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee(\B\wedge\A) & \text{(Commutativity,Absorption)}       \\[2mm]
                             & & \equiv & \Big(\big(\neg\B\wedge(\A\wedge\neg\B)\big)\vee\big(\neg\B\wedge(\neg\A\wedge\B)\big)\Big)\vee(\B\wedge\A) & \text{(Distributivity)}        \\[2mm]
                             & & \equiv & \Big(\big(\neg\B\wedge\neg\B\wedge\A\big)\vee\big(\neg\B\wedge\B\wedge\neg\A\big)\Big)\vee(\B\wedge\A) & \text{(Associativity Commutativity)}        \\[2mm]
                             & & \equiv & \Big(\big(\neg\B\wedge\A\big)\vee\big(\false\wedge\neg\A\big)\Big)\vee(\B\wedge\A) & \text{(Idempotency Negation)}        \\[2mm]
                             & & \equiv & \big((\neg\B\wedge\A)\vee\false\big)\vee(\B\wedge\A) & \text{(Neutrality)}        \\[2mm]
                             & & \equiv & (\neg\B\wedge\A)\vee(\B\wedge\A) & \text{(Neutrality)}        \\[2mm]
                             & & \equiv & (\A\wedge\neg\B)\vee(\A\wedge\B) & \text{(Commutativity)}        \\[2mm]
                             & & \equiv & \A\wedge(\neg\B\vee\B) & \text{(Distributivity)}        \\[2mm]
                             & & \equiv & \A\wedge\true & \text{(Negation)}        \\[2mm]
                             & & \equiv & \A & \text{(Neutrality)}        \\[2mm] 
    \end{array}\]
    }

Best Answer

Several issues:

  1. Don't use \[...\] inside an argument. Use $...$.

  2. Passed [t] to array to make it top aligned.

  3. Did not fix the fact that the box is a full \textwidth, despite it already being indented. You will need to reexamine that.

Here is the MWE. p.s. In the future, post a full working example, so we don't have to guess the meaning of things like \A, etc.

\documentclass{article}
\def\A{A}
\def\B{B}
\def\false{\ne}
\def\true{=}
\usepackage{graphicx,amsmath}
\begin{document}
\begin{itemize}
\item \resizebox{\textwidth}{!}{$\displaystyle
    \begin{array}[t]{lp{2mm}cll} 
    (\A \oplus \B) \oplus \B & & \equiv & \big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\oplus\B & \text{(Def of $\oplus$)}        \\[2mm]
                             & & \equiv & \Big(\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\wedge\neg\B\Big)\vee\Big(\neg\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\wedge\B\Big)& \text{(Def of $\oplus$)}        \\[2mm]
                             & & \equiv & \Big(\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\wedge\neg\B\Big)\vee\Big(\big((\neg\A\vee\B)\wedge(\A\vee\neg\B)\big)\wedge\B\Big)& \text{(De Morgan Laws Double Negation)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\big((\neg\A\vee\B)\wedge\B\wedge(\A\vee\neg\B)\big)& \text{(Associativity Commutativity)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\Big((\neg\A\vee\B)\wedge\big((\B\wedge\A)\vee(\B\wedge\neg\B)\big)\Big)& \text{(Distributivity)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\Big((\neg\A\vee\B)\wedge\big((\B\wedge\A)\vee\false\big)\Big)& \text{(Negation)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee\big((\neg\A\vee\B)\wedge\B\wedge\A\big) & \text{(Neutrality Associativity)}        \\[2mm]
                             & & \equiv & \Big(\neg\B\wedge\big((\A\wedge\neg\B)\vee(\neg\A\wedge\B)\big)\Big)\vee(\B\wedge\A) & \text{(Commutativity,Absorption)}       \\[2mm]
                             & & \equiv & \Big(\big(\neg\B\wedge(\A\wedge\neg\B)\big)\vee\big(\neg\B\wedge(\neg\A\wedge\B)\big)\Big)\vee(\B\wedge\A) & \text{(Distributivity)}        \\[2mm]
                             & & \equiv & \Big(\big(\neg\B\wedge\neg\B\wedge\A\big)\vee\big(\neg\B\wedge\B\wedge\neg\A\big)\Big)\vee(\B\wedge\A) & \text{(Associativity Commutativity)}        \\[2mm]
                             & & \equiv & \Big(\big(\neg\B\wedge\A\big)\vee\big(\false\wedge\neg\A\big)\Big)\vee(\B\wedge\A) & \text{(Idempotency Negation)}        \\[2mm]
                             & & \equiv & \big((\neg\B\wedge\A)\vee\false\big)\vee(\B\wedge\A) & \text{(Neutrality)}        \\[2mm]
                             & & \equiv & (\neg\B\wedge\A)\vee(\B\wedge\A) & \text{(Neutrality)}        \\[2mm]
                             & & \equiv & (\A\wedge\neg\B)\vee(\A\wedge\B) & \text{(Commutativity)}        \\[2mm]
                             & & \equiv & \A\wedge(\neg\B\vee\B) & \text{(Distributivity)}        \\[2mm]
                             & & \equiv & \A\wedge\true & \text{(Negation)}        \\[2mm]
                             & & \equiv & \A & \text{(Neutrality)}        \\[2mm] 
    \end{array}$
    }
    \end{itemize}
\end{document}

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