MESSAGE
| DATE | 2014-12-12 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [LIU Comp Sci] Fwd: Re: n-ary operations
|
From owner-learn-outgoing-at-mrbrklyn.com Fri Dec 12 02:25:54 2014
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Date: Fri, 12 Dec 2014 02:25:57 -0500
From: Ruben Safir
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To: learn-at-nylxs.com, ping-Tsai Chung
Subject: [LIU Comp Sci] Fwd: Re: n-ary operations
References: <20141211211322.9aa253a7.jklowden-at-speakeasy.net>
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wonder what I'm doing up at 3AM?
reading Computer stuff...
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Date: Thu, 11 Dec 2014 21:13:22 -0500
From: James K. Lowden
Newsgroups: comp.databases.theory
Subject: Re: n-ary operations
Message-ID: <20141211211322.9aa253a7.jklowden-at-speakeasy.net>
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On Thu, 11 Dec 2014 13:05:38 -0500
ruben safir wrote:
> On 12/11/2014 12:15 PM, Gene Wirchenko wrote:
> > R is an n-ary operation. It has n operands.
> >
> > S is an m-ary operation. It has m operands.
>
> >>blink<<
>
> Like a derivation of the work unary and binary?
Yes, exactly. From "A Relational Model of Data for Large Shared Data
Banks" (Codd, 1970):
"The term relation is used here in its accepted mathematical
sense. Given sets S1, S2, ? ? ? , Sn (not necessarily distinct), R is a
relation on these n sets if it is a set of n-tuples each of which has
its first element from S1, its second element from S2, and so on. We
shall refer to Sj as the jth domain of R. As defined above, R is said
to have degree n. Relations of degree 1 are often called unary, degree
2 binary, degree 3 ternary, and degree n n-ary."
--jkl
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