Q:

Double-hooked right arrow

I want to typeset a hooked right arrow (i.e. \hookrightarrow) with two hooks at the beginning (a notation for a compact embedding), but was unable to find it in the comprehensive symbol list. Is there a package providing such a symbol or what's a good way to create such a symbol myself?

A:

My own attempt (with original spacing of \hookrightarrow as reference):

\documentclass{article}
\usepackage{amsmath}
\usepackage{mathtools}

% double hooked arrow with length of normal hooked arrow
\newcommand{\doublehookrightarrow}{%
    \mathrel{\mathrlap{{\mspace{4mu}\lhook}}{\hookrightarrow}}
}

% double hooked arrow with length of hook + \hookrightarrow
\newcommand{\doublehookrightarrowalt}{%
    \lhook\joinrel\relbar\mspace{-12mu}\hookrightarrow
}

\begin{document}

$A \doublehookrightarrow B$, $\iota_{A \doublehookrightarrow B}$

$A \doublehookrightarrowalt B$, $\iota_{A \doublehookrightarrowalt B}$

% for spacing reference:
$A \hookrightarrow B$, $\iota_{A \hookrightarrow B}$

\end{document}

