To use stealth shaped arrow, I add this in preamble \usetikzlibrary{shapes,arrows,chains,positioning,calc} \usetikzlibrary{arrows.meta}  When compiling, the console gets stuck with (C:\MiKTex\tex\generic\pgf\frontendlayer\tikz\libraries\tikzlibraryautomata.code.tex) and there is no error message. MWE: \documentclass[11pt]{article} \usepackage{tikz} \usetikzlibrary{shapes,arrows,chains,positioning,calc} \usetikzlibrary{arrows.meta}  \begin{document}  \begin{tikzpicture}[scale=8]\centering \usetikzlibrary{automata,positioning} \tikzset{     %Define standard arrow tip     &gt;=stealth',     %Define style for boxes     punkt/.style={            rectangle,            rounded corners,            very thick,            text width=6.5em,            minimum width = 5em,            minimum height=4em,            text centered},     % Define arrow style     pil/.style={            -&gt;,            thick,            shorten &lt;=2pt,            shorten &gt;=2pt,} }   \node [punkt, draw = blue] at (0,0) {$x&gt;y$}; \node [punkt, draw = red] at (0.8, 0) {$x&lt;y$};  %  \node[] at (0.15, 0.03) (0up) {};  \node[] at (0.65, 0.03) (1up) {};  \path (0up) edge[pil, bend left=15] node [above] {A} (1up);   \node[] at (0.15, -0.03) (0down) {};  \node[] at (0.65, -0.03) (1down) {};  \path (1down) edge[pil, bend left=15] node [below] {B} (0down);  \end{tikzpicture}  \end{document}  My problem is that the MWE per se works well, but adding the same piece of code into my original tex file leads to the aforementioned problem. Update: Finally found the the &quot;MnonWE&quot;: \documentclass[11pt]{article} \usepackage{commath} \usepackage{tikz}  % arrows in tikz \usetikzlibrary{shapes,arrows,chains,positioning,calc} \usetikzlibrary{arrows.meta}  \begin{document}  \begin{tikzpicture}[scale=8] \tikzset{     %Define standard arrow tip     &gt;=stealth',     %Define style for boxes     punkt/.style={            rectangle,            rounded corners,            very thick,            text width=6.5em,            minimum width = 5em,            minimum height=4em,            text centered},     % Define arrow style     pil/.style={            -&gt;,            thick,            shorten &lt;=2pt,            shorten &gt;=2pt,} }   \node [punkt, draw = blue] at (0,0) {$\forall i:x_i&gt;y_i$}; \node [punkt, draw = red] at (0.8, 0) {$\forall i:x_i&lt;y_i$}; %  \node[] at (0.15, 0.03) (0up) {};  \node[] at (0.65, 0.03) (1up) {};  \path (0up) edge[pil, bend left=15] node [above] {A} (1up);   \node[] at (0.15, -0.03) (0down) {};  \node[] at (0.65, -0.03) (1down) {};  \path (1down) edge[pil, bend left=15] node [below] {B} (0down);  \end{tikzpicture} \end{document}  So the file fails to compile only when \usepackage{commath} is included in preamble and $\forall i:x_i&gt;y_i$ is used in the \node.
MWE:  \documentclass{minimal} \usepackage{commath, tikz} \begin{document} \begin{tikzpicture} \node {$:$}; \end{tikzpicture} \end{document}   When I compile this, pdfTeX enters an infinite loop. Why?
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