What is this symbol consisting of a horizontal line crossed by a rotated vertial line?

Question

I'm looking at the following symbol, between W and X, in an old PDF file:

and would like to use it in Math mode in my document, but can't figure it out which symbol it is. Is it a standard Math symbol? Any suggestions for symbols that look similar to it?

The PDF file is here: http://dl.acm.org/citation.cfm?id=74833, though it's not open access. The title of the paper is: "Scannerless NSLR(1) parsing of programming languages"

Answer 1

Never seen such a symbol, but you can define it; choose a better name.

\documentclass{article}
\usepackage{centernot}

\newcommand{\wrel}{% for ``weird relation''
  \centernot{\mathrel{-}\joinrel\mathrel{-}}%
}

\begin{document}
\[
W\wrel X
\]
\end{document}

Notes. I use the fact that TeX doesn't add space between consecutive relation symbols; \joinrel is a little negative space that counts as a relation symbol. Thus we get two superimposing minus signs (just like what's done for longer arrows). With \centernot we place the \not symbol exactly in the middle.

---

A different version using / instead of \not, so also \backslash can be employed instead.

\documentclass{article}

\makeatletter
\newcommand{\centersymbol}[2]{%
  \mathrel{\vphantom{#1#2}\mathpalette\center@symbol{{#1}{#2}}}%
}
\newcommand{\center@symbol}[2]{%
  \center@@symbol{#1}#2%
}
\newcommand{\center@@symbol}[3]{%
  \ooalign{\hss$#1\m@th#2$\hss\cr\hss$#1\m@th#3$\hss\cr}%
}
\makeatother

\newcommand{\wrel}{\centersymbol{/}{\mathrel{-}\joinrel\mathrel{-}}}
\newcommand{\lerw}{\centersymbol{\backslash}{\mathrel{-}\joinrel\mathrel{-}}}


\begin{document}
\[
W\wrel X \lerw Y
\]
\end{document}

Answer 2

The package MnSymbol defines \nleftrightline which looks similar:

\documentclass{standalone}
\usepackage{MnSymbol}
\begin{document}
  $W \nleftrightline X$
\end{document}