[Blindmath] No to Accessible LaTeX

[Susan Jolly]

LaTeX source is not a viable longterm solution for accessibility if for no 
other reason as it is not an international standard whereas MathML is.  And, 
by the way, sighted people do not read unrendered LaTeX source except for 
proofing something they've written themselves.

There are two possible solutions for making math accessible on the web. One 
is speech-based and the other is braille-based.

There are a growing number of TTS applications that convert MathML to speech 
in real time. Whether or not you personally use spoken math, this 
development is certainly a positive argument for the use of MathML as the 
basis for math on the Web.

Now to braille-based solutions.  Here there are many different 
possibilities.  One set of possibilities is based on the use of an ASCII 
math entry system: either one of the many flavors of LaTeX or some unrelated 
system  such as ASCIIMathML: 
http://www1.chapman.edu/~jipsen/mathml/asciimath.html  The other set of 
possibilities is based on the use of some standard braille system such as 
Nemeth.

For the benefit of those not familiar with refreshable braille let me pause 
to explain how braille readers read ASCII math. There are 94 different ASCII 
characters including the 52 small and capital Latin letters.  There are only 
63 six-dot braille cells so obviously there cannot be a one-for-one mapping 
of ASCII characters to six-dot braille or standard embossed braille. 
However, refreshable braille displays support eight-dot braille which 
provides for more than 94 possible braille cells. Braille displays show the 
ASCII characters using a mapping generally referred to as a computer braille 
table.  Different braille displays use different tables although they are 
generally similar. Commonly a seventh dot (at the bottom left of a braille 
cell) is used to distinguish the capital letters from the small ones and to 
distinguish five other ASCII characters.

I am not a braille reader but my understanding is that some braille readers 
are facile readers of  eight-dot computer braille and some aren't.

So there are thus a number of problems with using an ASCII math system to 
support braille-based accessibility. One is that these systems are 
inconsistent with the positive developments as far as MathML-based spoken 
math. A second reason is that none of these systems are what braille users 
first learn so there has to be relearning. The third is that it requires 
eight-dot braille which is not universally acceptable. Finally, there are 
dozens of ASCII math systems and it seems unlikely at this point that one of 
them would emerge as a standard solution for accessibility.

The big advantage is, of course, that ASCII math doesn't require further 
conversion in order to be displayed. Many braille readers have, of course, 
learned to decode some flavor of LaTeX on the basis that any accessibility 
is better than none. But since sighted people require electronic math to be 
rendered in order to be readable, it seems that true accessibility would 
entail rendering as well.

There are a growing number of applications designed to support realtime 
conversion from MathML to one or more of the standard braille math systems. 
However, if you prefer one of the ASCII maths, it is certainly possible to 
generate one of them from MathML as well.

Sincerely,
SusanJ



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