From: "David B. Benson" <dbenson@eecs.wsu.edu>
To: categories@mta.ca
Subject: RFN (Request for Notation)
Date: Sun, 26 Nov 2000 13:25:22 -0800 [thread overview]
Message-ID: <200011262125.NAA22532@kamiak.eecs.wsu.edu> (raw)
Dear Colleagues,
I am preparing notes for a sophomore (second year)
course, and I am finding several places wherein
I can find no standard notation. Your suggestions
will be most appreciated.
(1) Everybody knows that {(n,n+1) | n \in Z}
is the <<successor>> relation. What to call
the corresponding idea when the underlying
order is only a partial order?
I am currently using <<followers>> as in
phrases such as
``...the followers relation for the subsets
of the finite set {a, b, c}...''
in which ({a},{a,b}) is in the followers
relation, but {{a},{a,b,c}) is not, anymore
that (n,n+2) is in the successor relation.
Is there a better word than <<followers>>?
(2) I need a snappy name for an order pair in
a relation R. The books I have seem to just
say ``...the ordered pair (x,y) in relation R...''
The problem is that there are many uses of
ordered pairs, and this is a specific use,
a description of the fact that
x is R-related to y
by the fact that (x,y) \in R.
The word ``association'' will not do as this
has other meaning in computer science. I am
considered <<relator>> for an order pair in
a relation, but have the impression that this
word has been used for other purposes in the
literature.
(3) I badly need a good name for the sets
Nat_k = {n \in Nat | n < k }
These are widely used and I am surprised that
there is no satisfactory name in wide-spread use.
These are NOT the sets Z_k = Z mod k,
although the Nat_k form a system of distinct,
canonical representatives for the Z_k.
These are the set of array indices in computer
languages such as C and SML. In this use, the
Nat_k have nothing whatsoever to do with Z_k
and I certainly do not want to confuse the students!
Thank you in advance for any and all suggestions,
David
--
Professor David B. Benson (509) 335-2706
School of EE and Computer Science (EME 102A) (509) 335-3818 fax
PO Box 642752, Washington State University dbenson@eecs.wsu.edu
Pullman WA 99164-2752 U.S.A.
next reply other threads:[~2000-11-26 21:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-11-26 21:25 David B. Benson [this message]
2000-11-27 16:39 ` Justin Pearson
[not found] <200011271710.RAA07285@bruno.dcs.qmw.ac.uk>
2000-11-29 23:02 ` Paul Levy
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