From: Robert Miner <RobertM@dessci.com>

Date: Wed, 18 Jun 2003 10:29:17 -0500

Message-Id: <200306181529.h5IFTH006313@wisdom.geomtech.com>

To: gjc@inescporto.pt

CC: RobertM@dessci.com, www-math@w3.org

Date: Wed, 18 Jun 2003 10:29:17 -0500

Message-Id: <200306181529.h5IFTH006313@wisdom.geomtech.com>

To: gjc@inescporto.pt

CC: RobertM@dessci.com, www-math@w3.org

Hi. > Thank you for the reply. > Are you not confusing "stretchy" with "symmetric"? My problem is that > the symmetric attribute is not specified for any operator. I realize it > has a default value of 'true', therefore I conclude that symmetric=true > for all operators. Maybe this is intentional, but I find it a little > strange that *all* operators are symmetric by default... My apologies. You are correct. I was confusing stretchy with symmetric. However, I believe your interpretation is correct -- by default, all operators are symmetric. I suppose there could be some exceptional case that I'm overlooking, but in practice, I have only used symmetric="false" in two cases: 1) Matrix multiplication of non-square matrices: |a b| |A B C| |x y| |c d| |D E F| = |z w| |e f| This is hard to convey as ASCII art, but what one wants to avoid is something like: |a b| |A B C| |x y| |c d| |D E F| = |z w| |e f| | | | | 2) Complicated, deeply-nested expressions that are highly unsymmetric around the baseline, where symmetric parentheses look odd. There are probably more, but these are the only two cases I've encountered. However, both of them are clearly exceptional cases -- I'm using symmetric="false" to fix a rendering that looks odd otherwise. So the default is still true for all these fence characters. Let me know if you can think of an operator that really shouldn't be symmetric by default. I would be interested to know of one! --Robert ------------------------------------------------------------------ Dr. 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, 18 June 2003 11:29:49 GMT

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