Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 73D1F133798E for ; Wed, 4 May 2011 03:28:39 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 06349-06 for ; Wed, 4 May 2011 06:28:32 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from smarthost02.mail.zen.net.uk (smarthost02.mail.zen.net.uk [212.23.3.141]) by mail.postgresql.org (Postfix) with ESMTP id 4ABFD13364DE for ; Wed, 4 May 2011 03:28:31 -0300 (ADT) Received: from [82.68.43.86] (helo=mail.douglastechnology.co.uk) by smarthost02.mail.zen.net.uk with esmtp (Exim 4.63) (envelope-from ) id 1QHVZU-00017D-2Z; Wed, 04 May 2011 06:28:28 +0000 Received: from [192.168.16.207] (unknown [192.168.16.207]) by mail.douglastechnology.co.uk (Postfix) with ESMTPSA id AACF71264166; Wed, 4 May 2011 07:28:27 +0100 (BST) Message-ID: <4DC0F207.9080600@douglastechnology.co.uk> Date: Wed, 04 May 2011 07:28:23 +0100 From: Jack Douglas User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-GB; rv:1.9.2.17) Gecko/20110414 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Jaime Casanova CC: pgsql-docs@postgresql.org Subject: Re: boolean states References: <4DB7D7E3.6010403@douglastechnology.co.uk> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Originating-Smarthost02-IP: [82.68.43.86] X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.9 tagged_above=-5 required=5 tests=BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001 X-Spam-Level: X-Archive-Number: 201105/5 X-Sequence-Number: 6680 >> This sounds like an oxymoron to me. Perhaps that sentence should be changed >> to: >> >> The boolean type can have one of three states: "true" or "false" and >> "unknown". > if my boolean arithmetic is not wrong the above expression is bad. > better expressed is: "true", "false" or "unknown"... There are two kinds of people on this earth, those who understand boolean arithmatic and those who don't. I'm not one of them.