From: Richard Kaye <R.W.Kaye@bham.ac.uk>

Date: Fri, 19 May 2006 11:46:37 +0100

To: www-math@w3.org

Message-Id: <200605191146.37413.R.W.Kaye@bham.ac.uk>

Date: Fri, 19 May 2006 11:46:37 +0100

To: www-math@w3.org

Message-Id: <200605191146.37413.R.W.Kaye@bham.ac.uk>

This issue is perhaps peripheral to the original question, but it is interesting enough. I came across an identical problem this morning, when I was writing a quick and dirty stylesheet to convert XHTML+p-MathML into plain old HTML that could just about be readable by people without the right browser. (Basically, the only thing helpful in HTML is <sub> and <sup>.) I had to translate mfrac's as ((numerator)/(denominator)) and have ended up with many places where there are too many brackets. By the way, it just happens that I am currently writing a text on logic. In this, the duality between /\ and \/ is so important a pedagogical point that I would never break the duality by saying one binds more strongly than the other. (In fact that's my position at all times when and and or are notated this way - not just in this particular text. When they are notated && and || it's a different matter.) So I would always have brackets in this example. I guess you must be writing some software that has a default behaviour to omit brackets here. I trust that if I were using it there would be a way I could over-rule this default. You could go even further and reconsider whether you have the right default. But I honestly have no idea how many other people have a strong view on this point. Best wishes Richard On Thursday 18 May 2006 18:44, Michael Kohlhase wrote: > Interesting that you should ask just now, I have been stumbling over the > same thing a couple of days ago. The difference becomes interesting when > you try to do presentation with bracket elision. > > The general idea is that when we have > > <apply> > <or> > <apply><and><ci>a</ci><ci>b</ci></apply> > <apply><and><ci>c</ci><ci>d</ci></apply> > </apply> > > which should give a /\ b \/ c /\ d since /\ binds more strongly than \/. > > In such situations you want to have -(a+b), i.e. the unary minus > operator needs brackets but -1, i.e. the unary minus operator does not > here. > > Michael > > ------------------------------------------------------------------------- > Prof. Dr. Michael Kohlhase, Office: Research 1, Room 62 > Professor for Computer Science Campus Ring 12, > School of Engineering & Science D-28758 Bremen, Germany > International University Bremen tel/fax: +49 421 200-3140/-493140 > http://www.faculty.iu-bremen.de/mkohlhase <m.kohlhase@iu-bremen.de> > -------------------------------------------------------------------------- > > juanrgonzaleza@canonicalscience.com wrote: > > The chapter 4 of MathML 2.0 specification is far from precise at this > > point. > > > > Moreover, the tutorial > > > > [http://cnx.org/content/m9008/latest/] > > > > recommends next code > > > > <m:math> > > <m:apply> > > <m:minus/> > > <m:ci>x</m:ci> > > </m:apply> > > </m:math> > > > > to representing the negative of a variable, and recommends > > > > <m:math><m:cn>-1</m:cn></m:math> > > > > for the negative of a number. > > > > Whereas the next MathML tutorial > > > > [http://www.pragma-ade.com/general/manuals/mmlprime.pdf] > > > > says > > > > <blockquote> > > Although <cn>-37</cn> is valid, using minus is sometimes more clear. > > > > <math> > > <apply> <minus/> > > <cn> 37 </cn> > > </apply> > > </math> > > </blockquote> > > > > What is the difference if any between both encodings? > > > > What may be preferred? (I personally prefer unary usage of <minus/>) > > > > > > Juan R. > > > > Center for CANONICAL |SCIENCE)Received on Friday, 19 May 2006 10:45:13 GMT

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