# Re: Inverted (=reflected) N

• To: BNB@MATH.AMS.ORG
• Subject: Re: Inverted (=reflected) N
• From: Ulrik Vieth <vieth@thphy.uni-duesseldorf.de>
• Date: Fri, 6 Feb 1998 14:51:39 +0100
• Cc: C.A.Rowley@open.ac.uk, math-font-discuss@cogs.susx.ac.uk


> in this i agree with him.  however, regarding these particular names,
> i can't agree at all:

> ulrik:
>> Omega	Ohm
>> Delta	increment
>> Sigma	summation
>> Pi		product

>> These correspond to the many-to-many relationship between characters and
>> glyphs.

> chris:
>     No they do not; they are just synonyms for glyphs.

Sorry, but you misattributed this quotation.  It wasn't me who proposed.
I guess it was Berthold but never mind.

To comment on the subject, I believe it would be preferable to describe
glyph names by form rather than function (i.e. Omega, Delta, Sigma, Pi),
while refering to  function in a document markup.

If you write \increment in TeX or (&increment; in Math-ML), you could
still switch between different representations (i.e. geometric triangle,
upright or italic Delta) depending on the environment where it is used
(physics, math) or depending on the preferences of the publisher's style.

> these are abysmally badly chosen symonyms!  they certainly violate my
> sense of precision.  it's somewhat reasonable to use Omega or Delta
> for Ohm or increment,

even that is questionable, since an variable Omega might be upright in
math but italic in physics, while the unit Ohm should always be upright.
(One might even argue that pyhsical units are text not math and that
the units Ohm and the prefix micro (= upright mu) should be taken from
the text companion font).

> but if anyone used Sigma or Pi instead of
> summation or product in preparing an ams publication, they wouldn't
> get the correctly-shaped glyph, although it might still make sense to
> someone familiar with the math.  similarly, to use summation or product
> instead of the greek letter could yield extremely confusing nonsense.

I fully agree.  The only potential use I could see would be to define
a \smallsum or \smallprod operator using the glyphs \Sigma and \Pi.

Cheers, Ulrik.

P.S.  I have an unfinished discussion paper on the requirements for
markup of math-mode material in physics, which discusses the issues
regarding logial concepts (\vec, \tens, \unit, \chemical, \particle,
\increment, \variation, etc.) and their various representations.
Hope I get around to finish this paper someday.