ring definition(s)
Creighton Dement
crowdog at crowdog.de
Sat Jan 28 22:30:24 CET 2006
Dear Seqfans,
A sci.math thread recently mentioned the difference in the definition of
a ring given at Mathworld http://mathworld.wolfram.com/Ring.html and
Wikipedia http://en.wikipedia.org/wiki/Ring_theory : the former
specifies that multiplication defined for a ring not necessarily be
associative; the latter specifies not only that multiplication be
associative, but that it must also have a unit (this part of the
definition seems unusual to me).
If that is the case, shouldn't sequences such as
http://www.research.att.com/~njas/sequences/A037292
(Nonassociative rings with n elements) specify the definition being
used?
For the record, I consulted with my "Handbook of Discrete and
Combinatorial Mathematics" which gives the definition of ring I am used
to:
ring: an algebraic structure (R, +, *) where R is a set closed under two
binary operations + and *, (R, +) is an abelian group, R satisfies the
associative law for multiplication, and R satisfies the left and right
distributive laws for multiplication over addition.
Sincerely,
Creighton
-It's a shame when the girl of your dreams would still rather be with
someone else when you're actually in a dream.
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