From: David Carlisle <davidc@nag.co.uk>

Date: Mon, 24 Apr 2006 11:19:15 +0100

Message-Id: <200604241019.k3OAJFET032583@edinburgh.nag.co.uk>

To: Stephan.Semirat@ac-grenoble.fr

CC: www-math@w3.org

Date: Mon, 24 Apr 2006 11:19:15 +0100

Message-Id: <200604241019.k3OAJFET032583@edinburgh.nag.co.uk>

To: Stephan.Semirat@ac-grenoble.fr

CC: www-math@w3.org

Stephan, > Thank you. Is that what you mean : ⅆ and d are just > characters with no "content" meaning ? You need to be a bit careful about the terminology. The entity reference ⅆ has no significance at all in MathML. In many systems it is completely resolved by the XML parser before the MathML processor even sees the input. So the question is really not about entities but rather on whether the choice of character with Unicode number 8518 or number 100 has any "content" significance. As Stan has already indicated this depends a lot on what process is reading the MathML. The primary purpose of Presentation MathML is to express the presentation (that is, the layout forms used, although in a sufficiently general way that the same description can be used in different visual settings and aural renderings etc.) Of course it is possible for a system to read the presentation form and infer semantics, just as it is possible to read a printed page and infer semantics, but typically to do so you need to know some more context such as the subject area and notations used. So it may be that some processors find it easier to recognise an integral using character 8518 as the "d" but some may not. If you want to unambiguously mark up that your expression is an integral over a certain bound variable, then that is precisely the purpose of Content MathML. This is a general feature about mathematical notations, and nothing special about differential-d. Obviously some aspects such as searching might be simplified if everyone used the same notation for everything, but a) in practice that isn't going to happen and b) there would be some loss of cultural heritage and linguistic differences if it did. Again, Content MathML is there precisely to allow the mathematical meaning to be marked up while still allowing differences in notation. The choice of notation to use for the "d" is at exactly the same level as the choice of notation to use for (say) the tangent function. If everyone used "tan" for tangent then I, as a native English speaker, might find it a bit easier to search to find occurrences of the tangent function but MathML does not enforce this notation on the world. Have a look at the examples in http://www.w3.org/TR/arabic-math/ where tangent is expressed (in Presentation MathML) in four different ways, depending on the cultural notational style being used. tan, tg, and two different Arabic words. Just as Presentation MathML does not force you to use "tan" for tangent, it does not force you to use a double struck d in integrals, and the method of choosing your preferred notation is the same in either case, you put whichever characters that you want to use inside an mi element. > However, if for instance i want to translate my xhtml+mathml files to > tex, then &DifferentialD will be translated to \dd while d will be translated to d. > So i need to encode these two letter differently, no ? Not necessarily. If your \dd macro is a non-italic d then you could either use a mathvariant on the mi to specify roman, or just simply make your convertor detect the idiom of an mrow that starts with an integral sign and ends with d _something_ and convert it to whatever TeX markup you need. David ________________________________________________________________________ This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________Received on Monday, 24 April 2006 10:23:37 UTC

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