From: Bruce Miller <bruce.miller@nist.gov>

Date: Mon, 01 May 2006 12:00:53 -0400

Message-ID: <445630B5.1000609@nist.gov>

To: www-math@w3.org

Date: Mon, 01 May 2006 12:00:53 -0400

Message-ID: <445630B5.1000609@nist.gov>

To: www-math@w3.org

White Lynx wrote: >>By always using mover, you >>achieve a more _uniform_ encoding, and you make the markup less >>ambiguous > > > Consider q-dot. In Unicode there is unique representation q̇ > (q followed by combining dot above). In MathML it could be > <mover><mi>q</mi><mo>.</mo></mover> > <mover><mi>q</mi><mi>.</mi></mover> > <mover><mrow><mi>q</mi></mrow><mrow><mo>.</mo></mrow></mover> > <munderover><mi>q</mi><mi/><mo>.</mo></munderover> > <mover><mrow><mi>q</mi><mrow/></mrow><mo>.</mo></mover> > <mover><mi>q</mi><mo>·</mo></mover> > <mover><mi>q</mi><mo>̇</mo></mover> > <mover><mi>q</mi><mo>·</mo></mover> > <mover><mi>q</mi><mo>․</mo></mover> > <mover><mi>q</mi><mo>⋅</mo></mover> > I can't write all possibile ways of encoding q-dot in MathML > explicitly as their number is not finite. Not finite? I guess you're including an infinite nesting of mrow's, presumably to demonstrate that it is a bad idea to include a grouping construct in MathML. Several of your examples are invalid Unicode; combining characters are not to be used in isolation, which I would consider <mo>̇</mo> to be. Of the remaining infinite representations, several will actually _look_ different. The author may very well have reasons for choosing one over the other, although there's nothing inherent in the markup that tells the reader what distinguishes them. As has been discussed repeatedly on this list, this is either a strength or weakness, depending on your point of view. In any case, it appears that Unicode limits the author to only one choice --- and still doesn't say what he/she _meant_; Hmm... Your line of reasoning would seem to imply that _any_ math markup language, whether MathML, ISO12083, or yet to be invented, would be fatally flawed unless it forbid having fractions with 1 in the numerator and 2 in the denominator. After all, Unicode already defines ½! After filtering out the red herrings, you do suggest an interesting possibility with your first two cases: One could argue that * with <mo>.</mo> an operation on q is implied, possibly a time derivative, whereas * with <mi>.</mi> a composition is implied, representing a single composed identifier. (substitute "." with the glyph of your choice :> ) So, if we're taking votes :> I like Richard Kayes interpretation that Unicode composition would represent "weird atomic symbols", but MathML markup would represent operations. I would augment that with the exception that markup like that described above could be used to compose "weird atomic symbols" that might not have a Unicode equivalent (eg. g&COMBINING BULLET OVER; ) Of course, these have to be in the form of "suggested usage", rather than requirement, for all the reasons that have been discussed here. [...] > Did you take into account that there are hundred ways of encoding base in MathML > hundred ways of encoding dot (which dot?) and hundred ways of putting them together? 100^3\ll\infty -- bruce.miller@nist.gov http://math.nist.gov/~BMiller/Received on Monday, 1 May 2006 16:01:28 GMT

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