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Andrew Miller wrote:
> Hi all,
>
> I have been developing a plain-text input language for the content
> MathML in CellML documents (so that it can be efficiently edited by
> users). Although CellML is a declarative language rather than a
> procedural one, much of the expression syntax from languages like MATLAB
> and C-like languages can be re-used, and is likely to be familiar to
> many users. I have therefore tried to make my input language similar to
> these languages, where possible (for example, I have in-order operators
> like +, -, *, and / for plus, minus, times, divide, and a pre-order
> syntax, e.g. sin(x), for other operators). Please ask off-list for my
> bison grammar (a work in progress) if you would like to see it (I
> haven't checked it in to the public Subversion yet). Any opinions or
> suggestions on the overall structure of the language would be welcome.
>
> I am also seeking opinions on the most intuitive way to deal with the
> conversion between binary in-order operators like +. For example, if,
> within the input language, you have
> x = a + b + c + d + e + f
> a naive parser might create MathML like...
>
> <apply><eq/>
> <ci>x</ci>
> <apply><plus/>
> <apply><plus/>
> <apply><plus/>
> <apply><plus/>
> <apply><plus/>
> <ci>a</ci>
> <ci>b</ci>
> </apply>
> <ci>c</ci>
> </apply>
> <ci>d</ci>
> </apply>
> <ci>e</ci>
> </apply>
> <ci>f</ci>
> </apply>
> </apply>
>
> A slightly more complex parser might instead produce:
> <apply><eq/>
> <ci>x</ci>
> <apply><plus/>
> <ci>a</ci>
> <ci>b</ci>
> <ci>c</ci>
> <ci>d</ci>
> <ci>e</ci>
> <ci>f</ci>
> </apply>
> </apply>
>
> I would be interested in opinions on whether you feel this automatic
> translation from multiple binary in-order operators to a single
> pre-order operation makes sense (note: all CellML tools available now
> work with real numbers only, but future work could allow it to be
> extended to support other mathematical constructs. Using a definitionURL
> on an operator is technically valid CellML, but no tools can do anything
> with this either).
>
> The issue is complicated by what to do with bracketed expressions(which
> I currently allow, to override ambiguity). For example, a user could
> enter...
> x = (((((a + b) + c) + d) + e) + f)
> I would be interested to know if you believe that the first content
> MathML encoding or the second is more appropriate.

I think if the user has specifically entered the brackets then they
should be reflected in the generated MathML. If you think the second
chunk of MathML is more efficient (in some manner), then it might be
nice to prompt the user suggesting the removal of the brackets - i.e.,
present them with a display of the more efficient syntax and prompt for
a simple yes or no to choose whether the more efficient version gets
used. (and probably have an option to turn this feature on and off.)

>
> Best regards,
> Andrew Miller
>
> _______________________________________________
> cellml-discussion mailing list
> cellml-discussion at cellml.org
> http://www.cellml.org/mailman/listinfo/cellml-discussion

--
David Nickerson, PhD
Research Fellow
Division of Bioengineering
Faculty of Engineering
National University of Singapore
Email: david.nickerson at nus.edu.sg

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• [cellml-discussion] Content MathML editing language: Binary => n-ary syntax, Andrew Miller, 11/20/2006
  • [cellml-discussion] Content MathML editing language: Binary =>n-ary syntax, David Nickerson, 11/20/2006
    • [cellml-discussion] Content MathML editing language: Binary =>n-ary syntax, Alan Garny, 11/20/2006
    • [cellml-discussion] Content MathML editing language: Binary =>n-ary syntax, Andrew Miller, 11/20/2006
      • [cellml-discussion] Content MathML editing language: Binary=>n-ary syntax, David Nickerson, 11/20/2006
        • [cellml-discussion] Content MathML editing language: Binary=>n-ary syntax, Poul Nielsen, 11/21/2006
  • Message not available
    • [cellml-discussion] Content MathML editing language: Binary => n-ary syntax, Andrew Miller, 11/20/2006
  • [cellml-discussion] Content MathML editing language: Binary => n-ary syntax, Shane Blackett, 11/24/2006

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