# Undefined control sequence \subsetneq

\documentclass[a4paper,oneside,titlepage,12pt]{article}

\usepackage[cm-default,no-math]{fontspec}
\usepackage{xunicode}
\usepackage{xltxtra}
\usepackage{amsmath}
\usepackage{xgreek}

\setmainfont[Mapping=tex-text]{DejaVu Sans}
\parindent=0in

\begin{document}

$A \subseteq B$ \\
\\
$C \subsetneq D$

\end{document}


the first equation appears right the second as CD with no symbol in between.

I also get the following error message from xelatex:

! Undefined control sequence.
l.16 $C \subsetneq D$
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., \hobx'), type I' and the correct
spelling (e.g., I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
Underfull \hbox (badness 10000) in paragraph at lines 14--17
[]
[1
] (./basic.aux) )


if I add \usepackage{amssymb} I get the following error message

! LaTeX Error: Command \Finv' already defined.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.231 ...ol{\Finv} {\mathord}{AMSb}{"60}
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
! LaTeX Error: Command \Game' already defined.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.232 ...ol{\Game} {\mathord}{AMSb}{"61}
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
! LaTeX Error: Command \beth' already defined.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.237 ...ol{\beth} {\mathord}{AMSb}{"69}
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
! LaTeX Error: Command \gimel' already defined.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.238 ...ol{\gimel} {\mathord}{AMSb}{"6A}
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
! LaTeX Error: Command \daleth' already defined.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.239 ...ol{\daleth} {\mathord}{AMSb}{"6B}
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
) (/usr/share/texmf-texlive/tex/xelatex/xgreek/xgreek.sty
File: xgreek.sty 2008/06/22 v2.0 Package xgreek.sty'
Package xgreek' version 2.0 by Apostolos Syropoulos
\@attic@num=\count98
) (./basic.aux)
\openout1 = basic.aux'.

-
You have to load amssymb to be able to use \subsetneq –  karlkoeller Nov 2 '13 at 16:19
If you troll through the contents of How to look up a symbol or identify a math alphabet? you'll probably find that you need amssymb. –  Werner Nov 2 '13 at 16:22
I don't get those errors at all. Did you load some package that is not in your example? Do you possibly have a corrupted version of amssymb.sty? Mine has file length 13829 bytes. –  Dan Nov 3 '13 at 0:06
I have tried amssymb but I still get error messages. Regarding the size of amssymb.sty I have -rw-r--r-- 1 root root 13613 Jun 30 2009 /usr/share/texmf-texlive/tex/latex/amsfonts/amssymb.sty –  Testing Nov 14 '13 at 23:05
Does any of those packages define \Game or \Finv besides amssymb? Anyway you could try to open the style file and compy the \DeclareMathSymbol` for the desired command into your preamble, as a last resort. I'll try compilig your code very soon. –  MickG Nov 22 at 19:37