# How do I redefine the QED symbol to be a Unicode character?

I want to redefine the default QED symbol to be some Unicode character from the big list, e.g. 26C4, a snowman. I wrote this MWE:

\documentclass[12pt]{article}

\usepackage{amsmath, amsthm, amssymb}
\usepackage{etoolbox}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{mathtools}
\usepackage{microtype}

\DeclareUnicodeCharacter{26C4}{\snowman}
\renewrobustcmd{\qedsymbol}{\snowman}

\newtheorem{theorem}{Theorem}[section]

\begin{document}
\section{Introduction}

\begin{theorem}
a = b
\end{theorem}

\begin{proof}
Trivial.
\end{proof}
\end{document}


but at compilation, it throws an error:

! Undefined control sequence.
\qedsymbol ->\snowman


I'm using Miktex 2.9 on Windows 7 x64 with PDFLatex. Am I simply not loading the correct font? I tried to follow the Wikibooks guide to using Unicode in Latex, which is where I found the DeclareUnicodeCharacter command.

• You're providing no definition for \snowman. But the fonts you're loading don't have it anyway. Feb 24 '15 at 20:43
• @egreg I guess I thought that the \DeclareUnicodeCharacter defined the command. Feb 24 '15 at 20:44
• You are reading the command backwards, the declaration says that if you have the character U+2C64 (⛄) in the file, to execute the command \snowman (which you then need to define in some way). Feb 24 '15 at 20:49

The Unicode reference is a red herring really, for pdftex you would need a classic (256 character) font that has such a character. There may be such a font but it is simpler really just to use a graphic. best would be a scalable image. If you have a system font with it in, make a small pdf, but a bitmap image also works, I just drew one. You can then define \snowman by

\documentclass[12pt]{article}

\usepackage{amsmath, amsthm, amssymb}
\usepackage{etoolbox}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{mathtools}
\usepackage{graphicx}
\usepackage{microtype}

\renewrobustcmd{\qedsymbol}{\includegraphics[height=1em]{snowman}}

\newtheorem{theorem}{Theorem}[section]

\begin{document}
\section{Introduction}

\begin{theorem}
a = b
\end{theorem}

\begin{proof}
Trivial.
\end{proof}
\end{document}