Problem with \widehat{=} and $

Question

when I´m using \widehat{=} or \hat{=} i get an error. Also the pdf output isn´t formatted as it should be.

\textbf{foo:} for example \textit{city} \widehat{=} \textit{attribute} and\texit{new york} \widehat{=} \textit{object}.

It should look like this:

• foo: for example city ≙ attribute and new york ≙ object.

What am I missing?

Answer 1

Use \mathrel{\widehat{=}} to get the correct spacing around the relation symbol.

As already noted in the comments, the whole contructions only works in math mode, i.e., either inside a pair of $ signs, or in a mathematical environment like equation.

Answer 2

Since your symbol seems to be used in text mode, I suggest defining a macro, that makes easier inputting the text.

\documentclass{article}

\newcommand{\is}[2]{\textit{#1}$\;\widehat{=}\;$\textit{#2}}

\begin{document}

For example \is{city}{attribute} and
\is{New York}{object}.

\end{document}

Answer 3

Try this (\equalhat):

\documentclass{article}
\usepackage{scalerel,stackengine,amsmath}
\newcommand\equalhat{\mathrel{\stackon[1.5pt]{=}{%
  \stretchto{\scalerel*[\widthof{=}]{\wedge}{\rule{1ex}{3ex}}}{0.5ex}}}}

\begin{document}

$\equalhat$

\end{document}