From: Robert Miner <RobertM@dessci.com>

Date: Wed, 20 Jun 2001 15:09:38 -0500

Message-Id: <200106202009.PAA22795@wisdom.geomtech.com>

To: dreamthnk@hotmail.com

CC: www-math@w3.org

Date: Wed, 20 Jun 2001 15:09:38 -0500

Message-Id: <200106202009.PAA22795@wisdom.geomtech.com>

To: dreamthnk@hotmail.com

CC: www-math@w3.org

Hi. > 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>±</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> or maybe <apply> <or/> <apply><plus/><cn>3</cn><cn>5</cn></apply> <apply><minus/><cn>3</cn><cn>5</cn></apply> </apply> depending on the context. --Robert ------------------------------------------------------------------ Robert Miner RobertM@dessci.com MathML 2.0 Specification Co-editor 651-223-2883 Design Science, Inc. "How Science Communicates" www.dessci.com ------------------------------------------------------------------Received on Wednesday, 20 June 2001 16:09:48 UTC

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