# How to deal with the confliction between PHP-Markdown and MathJax?

I use PHP-Markdown plugin in WordPress. In order to show the formula beautifully, I add some code to use MathJax.

Like this:

<script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
extensions: ["tex2jax.js"],
jax: ["input/TeX", "output/HTML-CSS"],
tex2jax: {
inlineMath: [ ['$','$'], ["\$","\$"] ],
displayMath: [ ['$$','$$'], ["\$","\$"] ],
processEscapes: true
},
"HTML-CSS": { availableFonts: ["TeX"] }
});
</script>


But something wrong happens. Once my formula contains at least two underlines, the MathJax doesn't work. Such as $$P_1, P_2$$, and the words between the two underlines will be transformed to italic.

The formula will be transformed by PHP-Markdown first, and it can't be transformed by MathJax again.

Could you help me?

But Markdown-extra is not perfect either and I've seen some other quirks with respect to emphasis, e.g. Let $(y_n)_{n\in \omega}$ enumerate ${ x_i: i \in \bigcup_{n\in \omega} A_n}$ will trip it up.