RE: LeftRightArrow equivalence operator?

Mr. Miner,

Thanks for your reply and for your work on MathML.
Sorry if my question was not clear.
I found the Unicode character and the MathML alias I was looking for,
but I guess I was asking more about MathML,
where's the content mark-up element for "equivalence", "biconditional"?
As I understand it, as a MathML user I can't add a content mark-up element
without editing the mathml.dtd.
Maybe I don't have a question as much as a suggestion for an addition to the
content mark-up elements in some future rev.

Thanks again,
Hugh J. Devlin

> -----Original Message-----
> From: Robert Miner [mailto:rminer@geomtech.com]
> Sent: Saturday, October 09, 1999 12:46 PM
> To: devlinh@nwu.edu
> Cc: www-math@w3.org
> Subject: Re: LeftRightArrow equivalence operator?
> Hi Hugh,
> > The MathML rec includes a RightArrow, implies content element, but
> > apparently absent is a LeftRightArrow, equivalence operator. Unless I'm
> > missing something?
> I think you're missing something.  I assume you are using TeX
> terminology here, and are thinking of a double arrow with heads at
> both ends typically indicating the (logicial) equivalence "if and only
> if".
> The official unicode point for that character is 0x21D4 and its
> official unicode entity name is ⇔.  In MathML it also has a
> a couple of aliases which are valid -- ⇔ and
> ⇔.
> For some reason that I don't know, the TeX name lost out here, and the
> obvious guess -- ↔ -- is actually a synonym for TeX's
> \leftrightarrow.
> In general, most of these naming issues came up as uncomfortable
> compromises.  MathML has *lots* more characters (and specifically
> arrows) than TeX and though in general we tried very hard to stay
> compatible with TeX names, that wasn't always possible, especially
> since TeX, LaTeX, AMSTeX etc are not always consistent amongst
> themselves.
> --Robert
> ----------------------------------------------------------------
> Robert Miner                          http://www.webeq.com
> Geometry Technologies, Inc.           email: rminer@geomtech.com
>                                       phone: 651-223-2884
> ----------------------------------------------------------------

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