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Re: Math in the Page Authoring Guidelines

From: Charles McCathieNevile <charles@w3.org>
Date: Wed, 9 Dec 1998 16:09:06 -0500 (EST)
To: WAI UA group <w3c-wai-ua@w3.org>
cc: WAI GL <w3c-wai-gl@w3.org>, raman@adobe.com
Message-ID: <Pine.LNX.4.04.9812091552210.28821-100000@tux.w3.org>
T V Raman's Aster (as Jason has said, I think) is an example of a good
piece of third party technology which translates algebraic expressions (in
this case marked up in LaTeX I believe) into speech. It includes the
ability to chuck the equations, providing the kind of contextualisation
available visually, as well as an aural style sheet to provide
distinctions.

The area in which that is important is the User Agent group, and the issue
for them to consider is how to present Mathematical equations (or
chemistry, or written music, or whatever).

The issue for the Page Authors is how to present mathematical (or
chemical, or musical or whatever) material which requires presentation and
markup that falls outside of standard HTML and what it provides. THere are
a couple of relevant guidelines:

Where possible use a w3c technology...

Bingo. MathML

... where this results in material that does not transform gracefully you
must provide an alternative version of the content that is accessible

So far as I know MathML does not transform gracefully. So use a method
that does, such as the example of including a MathML equation as well as
an image of it (for sighted users of non-MathML compliant browsers) and a
textual description of it (for anybody - if the description is good then
the accessibility will be ordinary. If the description is bad then the
accessibility will be excruciatingly difficult. But that's miles ahead of
impossible)

eg: (I have also included a latex description for those who can read it.
But the type is probably wrong)

<OBJECT TYPE="text/MathML" DATA="equation1.xml" TITLE="equation one in
MathML markup">
  <OBJECT TYPE="text/latex" DATA="equation1.tex" TITLE="equation one in
latex markup">
     <OBJECT TYPE="image/gif" DATA="equation1.gif" TITLE="equation one as
a GIF image">
        A long and very accurate text description, with links to pieces of
the equation, so that it can be naturally chunked or listened to as a
whole, depending on concentration levels:
        <P>A equals One
     </OBJECT>
  </OBJECT>
</OBJECT>

--Charles McCathieNevile
W3C Web Accessibility Initiative (visiting)
email: charles@w3.org telephone: +1 (617) 258 8143
mail: LCS, 545 Technology sq., Cambridge MA, USA
http://purl.oclc.org/net/charles

On Wed, 9 Dec 1998, Al Gilman wrote:

  The expression complexity of visual symbolic language for
  mathematics breaks the complexity management guidelines for
  spoken information.  I see a lot of equations in print with too
  many productions in them to be spoken comprehensibly in one
  sentence.  It's like one needs to sic a composition teacher on
  them and get the argument restated as a sequence of shorter
  sentences.
  
  Another way to state this is: "Here is another domain, like
  translating programs between programming languages, where a
  purely syntactic transformation may yield less-than-desirable
  results."
  
  The risk associated with expression complexity is greater in
  speech than in print.  Loss of tracking kicks in at a lower
  expression complexity.  Articulating some mathematical utterance
  as speech may work better if a whole article is compiled, and not
  just the text (including math symbol structures) transliterated.
  
  The shape of the compile process would be something like a) build
  a knowledge base from the whole article including symbolic
  exhibits and verbal voice-over b) segment it into feasible verbal
  paragraphs for readout from the knowledge base, c) code-generate
  the latter into fluent verbal language.  Or tolerable.
  
  Al
  
  
Received on Wednesday, 9 December 1998 16:09:08 GMT

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