- From: Michael Kohlhase <m.kohlhase@iu-bremen.de>
- Date: Thu, 18 May 2006 19:44:01 +0200
- To: juanrgonzaleza@canonicalscience.com
- Cc: www-math@w3.org
- Message-ID: <446CB261.8010506@iu-bremen.de>

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 Thursday, 18 May 2006 17:44:15 UTC