Incompatibility with MTPro Lite and breqn packages

Question

There is an incompatibility with the MTPro Lite and breqn packages that breaks the \implies symbol definition.

At my sample code:

\documentclass{article}

\usepackage[lite,subscriptcorrection,slantedGreek,nofontinfo]{mtpro2}
\usepackage{mathtools}
\usepackage{fixmath}
\usepackage{breqn}

\begin{document}

Let $x\implies y$. Can you see the problem?

\end{document}

Is there any way to fix it?

Answer 1

The problem seems to be in that mtpro2 uses a different code for \Relbar than the standard one.

Here's a fix, but I don't know if it breaks something else.

\documentclass{article}

\usepackage[lite]{mtpro2}
\usepackage{amsmath}
\usepackage{breqn}

\AtBeginDocument{%
  \edef\Relbar{\mathord{\mathchar\the\numexpr\Relbar-"3000}}%
}

\begin{document}

$a \Longrightarrow b \Longleftarrow c$

$a \implies b \impliedby c$

\end{document}