TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am trying to use a symbol mapped by the tag \lrtimes in Math mode, but I am getting error. Here is what I am doing.

Sys_1 \stackrel{\text{\tiny def}}{=} (Appl \parallel Appl) \lrtimes  WS

The \stackrel{\text{\tiny def}}{=} is a latex code for 'is defined as' operator which works fine in my other formulas.

The log message(from texmaker) reads as below:

! Undefined control sequence. ...}{=} (Appl \parallel Appl) \lrtimes WS l.69 \end{align*} The control sequence at the end of the top line of your error message was never \def'ed.

What is wrong in this case?

share|improve this question
While code snippets are useful in explanations, it is always best to compose a fully compilable MWE that illustrates the problem including the \documentclass and the appropriate packages so that those trying to help don't have to recreate it. – Peter Grill Nov 30 '12 at 5:23
Ya sure, i agree – Shafi Nov 30 '12 at 5:39
the name \bowtie also represents the same symbol, and it's already present in latex. – barbara beeton Nov 30 '12 at 13:52
up vote 1 down vote accepted

To use \lrtimes you need \usepackage{pxfonts} in the preamble:

enter image description here


Sys_1 \stackrel{\text{\tiny def}}{=} (Appl \parallel Appl) \lrtimes  WS
share|improve this answer
Thanks for the answer. The reason for the error is that pxfonts.sty file is missing. – Shafi Nov 30 '12 at 5:34
One should note that this globally changes the document font. – egreg Nov 30 '12 at 7:51

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.