W3C home > Mailing lists > Public > www-math@w3.org > June 2001

Re: content for characters

From: William Arthur Naylor <bill@scl.csd.uwo.ca>
Date: Wed, 20 Jun 2001 17:06:01 -0400 (EDT)
To: Robert Miner <RobertM@dessci.com>
cc: dreamthnk@hotmail.com, www-math@w3.org
Message-ID: <Pine.LNX.4.21.0106201656160.10588-100000@millennium.scl.csd.uwo.ca>
On Wed, 20 Jun 2001, Robert Miner wrote:

> 
> > i was just wondering if there was a way to apply certain characters, for 
> > example "plusminus" or "plusmn" as content mathml as opposed to leaving it 
> > as presentation mathml since the symbol is not just a constant, but rather 
> > represents an operation.
> 
> This is kind of a tricky case.  The plusminus symbol is usually really
> used as a shorthand for  two separate operators.  One could try to
> define a plusminus operator that maps from RxR -> RxR, so that
> 
> 
>   3 plusminus 5 = (8, -2)
> 
> or something like that, but then you have problems extending all your
> other operators to work on lists, e.g what does (3 plusminus 5) * 2
> mean?  The * isn't ordinary multiplication anymore, since the operand
> on the left is now an ordered pair.
> 
> For content encoding, probably the better way to go is to use the
> logic contructs, or possible the list construct to write down both the
> result of adding and subtracting the arguments.  Thus, the presentation
> MathML
> 
> <mrow><mn>3</mn><mo>&plusmn;</mo><mn>5</mn></mrow>
> 
> best corresponds to a content encoding like
> 
> <list>
>   <apply><plus/><cn>3</cn><cn>5</cn></apply>
>   <apply><minus/><cn>3</cn><cn>5</cn></apply>
> </list>

This would be nice, though the ordering is artificial, it would be better
if we used/had some sort of tuple construct

> 
> <apply>
>   <or/>
>   <apply><plus/><cn>3</cn><cn>5</cn></apply>
>   <apply><minus/><cn>3</cn><cn>5</cn></apply>
> </apply>
> 

of course this should return a boolean, and in fact makes no sense when
applied to plus and/or minus, unless their meanings where overridden using
the 'definitionURL' attribute (what would that mean for 'minus'!),

Bill.

-- 
Received on Wednesday, 20 June 2001 17:06:08 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Saturday, 20 February 2010 06:12:50 GMT