Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.icl.net!proxad.net!fr.ip.ndsoftware.net!news.newsland.it!ilaria.aioe.org!aioe.org!not-for-mail From: "x" Newsgroups: comp.databases.theory Subject: Re: So what's null then if it's not nothing? Date: Thu, 24 Nov 2005 10:10:56 +0200 Organization: Aioe.org NNTP Server Lines: 29 Message-ID: References: <1132227541.584895.246870@o13g2000cwo.googlegroups.com> <437c77ee$1@news.fhg.de> <1132233342.792567.129540@g14g2000cwa.googlegroups.com> <437c85de$1@news.fhg.de> <1132237398.838820.240080@g47g2000cwa.googlegroups.com> <437c989a$1@news.fhg.de> <1132241202.915606.116130@o13g2000cwo.googlegroups.com> <437ca639$1@news.fhg.de> <6ugpn1llgd1tqcgkn92f32v9u5bvv73q2k@4ax.com> <437df0b2$1@news.fhg.de> <1132453410.574645.187030@f14g2000cwb.googlegroups.com> <1132574034.654280.270710@o13g2000cwo.googlegroups.com> NNTP-Posting-Host: s9btCjTiVvvsgWfav5q8uQ.user.domitilla.aioe.org X-Complaints-To: abuse@aioe.org X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-Priority: 3 X-Newsreader: Microsoft Outlook Express 6.00.2800.1437 X-MSMail-Priority: Normal Xref: dp-news.maxwell.syr.edu comp.databases.theory:34623 "JOG" wrote in message news:1132574034.654280.270710@o13g2000cwo.googlegroups.com... > > Consider the question "When did you stop beating your wife?" > > > > Someone who is unmarried can't respond with a date, even though they > > know the answer. The correct answer is Null, but this does not mean that > > the answer is unknown. Any debate that works on the assumption that Null > > necessarily means unknown is based on a false premise and will possibly > > produce paradoxical conclusions. > > Well this is exactly the point. It is not the question that we should > care about. In fact the question should be almost irrelevant - it's the > answers that the database should be concentrating on encoding (and none > will be "Null"). Extrapolating out answers for a tweaked question: > > "When did meet your wife?" - 2001 > "When did meet your wife?" - I am not married > "When did meet your wife?" - I can't remember. > > yields 3 facts as a result. And these all fulfill different predicates. > Go figure. Yet these forms of responses are so prevalent in human > discourse, surely the indication is that the DBMS systems we are > currently presented with (by which I refer to the management systems > themselves and not the RM underpinnings) are insufficient. "When did meet your wife?" - What's a wife ? :-)