mixed fractions for MathML 3?

The MathML IG is looking to gather a list of features to be considered for a possible MathML update (MathML 3).  I'd like to suggest better support for mixed fractions.

A mixed fraction is a fraction that consists of an integer followed by a fraction such as
    
See Eric Weissteins amusing entry mathworld.wolfram.com/MixedFraction.html.  Despite Eric's admonishment to use this form only in the kitchen, they are common in elementary school math.

For display, I think that there is typically some space added between the integer and the fraction.  I'm not sure how much space is appropriate, which probably leads to rendering inconsistencies for those trying to author/display mixed fractions.

Computation systems most likely would interpret this as multiplication without some modification.  The Nemeth math braille code writes mixed fractions differently than ordinary fractions, so some distinction is important for accessibility reasons (it would help speech renderers also).

There are probably several tweaks to presentation math that would solve the problem, but solutions are best left for the MathML 3 committee to decide upon.

Mixed fractions are often used along side of improper fractions in elementary school math, so content MathML (which only has the abstract notion of a fraction), isn't really appropriate for discussing them (one could use msemantics or a definition URL if you are desperate) .  Perhaps some general attribute for content mathml that helps guide translation into presentation form would be of use.  I believe someone suggested such an attribute in another context at one point.

Neil Soiffer                     email: neils@dessci.com
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