[tex4ht] [bug #278] Wrong mathml with $\langle$

[Michal Hoftich]

> 
> On Thu, Mar 31, 2016 at 4:34 AM, Michal Hoftich <michal.h21 at gmail.com> wrote:
> 
>     This sample document:
> 
>     -------------
>     \documentclass{article}
> 
>     \begin{document}
> 
>     hello $\langle$
>     \end{document}
>     ----------
> 
>     generates wrong mathml:
> 
> 
> I think the source is nonsense -- or, at best, ambiguous -- if translation to
> HTML with MathML is envisioned.  For example, is this an abuse of math because
> the user does not know about     extless or how to obtain U+2329?  If it's indeed
> intended as math, is this an attempt to use \langle (U+27E8) as an ordinary
> math symbol other than a group opener?  Or is it intended to be the empty group
> properly marked up with
> "\left\langle{}\right." ?
> 

It is based on earlier message from today, where OP used it for encoding
brackets around email address. It could be seen (and I agree that it is)
as abusing of math mode, but this construct seems as quite common when I
googled it. As I am not a math expert, I am not sure whether is it
legitimate to use this in math or not. If it isn't and it is really just
dirty hack to get angles in text, then we maybe just should educate
users that it is wrong. But in this case we may get occasional bug
reports about invalid tex4ht output from users following advice on the
internet :)

Best regards,
Michal