Path: news.cambrium.nl!textnews.cambrium.nl!feeder3.cambriumusenet.nl!feed.tweaknews.nl!87.79.20.101.MISMATCH!newsreader4.netcologne.de!news.netcologne.de!news.glorb.com!Xl.tags.giganews.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.megapath.net!news.megapath.net.POSTED!not-for-mail NNTP-Posting-Date: Thu, 11 Dec 2014 20:13:22 -0600 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@speakeasy.net> References: X-Newsreader: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64--netbsd) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Lines: 25 X-Usenet-Provider: http://www.giganews.com NNTP-Posting-Host: 209.166.36.60 X-Trace: sv3-Mn9WVV2vY027S6J4V9tmt+ICQKl00hvkFZ0Zlqxk4JcHmzMTO750/Zj5sX8DhgPW+40VcWwcvKEB8Sm!+UdsBzXeQlrJMmDaVkgSqmY5x4iCs8SVhgXcPq088eJuYX1QBZGuIWTBb6lfkdBfZkhdTE80QkII!+rJrpu7WEkVOnADaVKqj/K2XBxjZhLBR X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 2028 Xref: news.cambrium.nl 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. > >=20 > > S is an m-ary operation. It has m operands. >=20 > >>blink<< >=20 > 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