From: Kent Karlsson (kentk@md.chalmers.se)
Date: Thu May 29 2003 - 10:01:22 EDT
Michael Everson wrote:
> >(Remember that the empty set symbol really was an O with stroke,
> >originally!)
>
> Surely a 0 with stroke, not a O with stroke.
The empty set sign was originally definitely the Norwegian/Danish letter
CAPITAL O WITH STROKE. It never was related at all to a ZERO with
stroke.
See http://members.aol.com/jeff570/set.html (which I referred to
earlier,
though it unfortunately uses the term "null set"...; but it also (quite
rightly)
uses U+00D8 for the empty set symbol, rather than U+2205; the choice is
stylistic):
----------------------------------------------------------
The null set symbol (Ř). André Weil (1906-1998) says in his
autobiography
that he introduced the symbol:
Wisely, we had decided to publish an installment establishing
the system
of notation for set theory, rather than wait for the detailed
treatment that
was to follow: it was high time to fix these notations once and
for all, and
indeed the ones we proposed, which introduced a number of
modifications
to the notations previously in use, met with general approval.
Much later, my
own part in these discussions earned me the respect of my
daughter Nicolette,
when she learned the symbol Ř for the empty set at school and I
told her that
I had been personally responsible for its adoption. The symbol
came from the
Norwegian alphabet, with which I alone among the Bourbaki group
was familiar.
The citation above is from page 114 of André Weil's The Apprenticeship
of a
Mathematician, Birkhaeuser Verlag, Basel-Boston-Berlin, 1992. Translated
from
the French by Jennifer Gage. The citation was provided by Julio González
Cabillón.
This letter is used in the Norwegian, Danish and Faroese alphabets.
------------------------------------------------------------
/kent k
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