Talk:Boolean logic

message: Is there an official order of operations for boolean logic, like there is for standard mathematical operations? -Ravedave (talk) 23:13, 25 March 2008 (UTC)
replies: text: Usually, when people have to manipulate expressions with multiple operations, they make up an order of operations. One common convention is that parentheses are done first, then negation, then conjunction and disjunction are done from left to right, then implication is done from left to right. Also, it's common to take A \to B \to C to mean A \to (B \to C), which is important because implication is not associative. But not all authors follow all these rules, and some authors might have other conventions (perhaps conjunction is done before disjunction) so you have to double-check each text. — Carl (CBM · talk) 00:26, 26 March 2008 (UTC)

text: I pretty much agree.  The parens comes first, then NOT.  The only debatable part is whether AND or OR has higher priority.  I'd always use parens to make it clear. StuRat (talk) 03:06, 28 March 2008 (UTC)
replies: text:  That is totally insane. Everyone knows what 2 * 3 + 4 equals, I can't believe there isn't a standard rule for what "true and false or true" means. Hrm I guess you learn something every day. -Ravedave (talk) 03:54, 28 March 2008 (UTC)
replies: text: "(true and false) or true" and "true and (false or true)" are both true, so the syntactic ambiguity doesn't make this semantically ambiguous. Truly ambiguous formulae of the form "P and Q or R" are only "false and false or true" and "false and true or true". In Boole's notation, conjunction was written as algebraic multiplication and disjunction as addition, and PQ+R meant, as in standard algebra, (PQ)+R. This is probably the reason why some people give "and" precedence over "or" – which means you need to exercise more care in order to apply De Morgan's laws faultlessly. Not everyone agrees what 1/2·3 means either; is it (1/2)·3 or 1/(2·3)?  --Lambiam 09:26, 28 March 2008 (UTC)
replies: text: true or false and false is a better example.  (true or false) and false = false; true or (false and false) = true. I thought "and before or" was a rule, but I can't find it anywhere...  — Preceding unsigned comment added by 216.234.101.74 (talk) 13:38, 19 September 2013 (UTC)
thread_title:  order of operations 

message: I suggest a rewrite for the entire article because of the manner in which it is written. This is supposed to be an encyclopediac entry containing pure fact, not a tutorial.--Trehansiddharth (talk) 00:11, 27 October 2009 (UTC)
replies: text: This article is a known problem. A number of people tried to solve it at various times. Most notably, an expert (Vaughan Pratt) rewrote this very article several times. The problem is that the unencyclopedic idiosyncrasies and inaccuracies in this article are being defended by an uncooperative editor who believes he is an expert on teaching the topic. If you rewrite this article once more, the odds are that after a while this editor will notice that 'his' article has disappeared once again and will once more resurrect it by creating yet another fork. This will add yet another article to the disambiguation page Boolean algebra. Relevant policy links: WP:OWN, WP:POVFORK. Hans Adler 13:32, 28 October 2009 (UTC)
replies: text: While I don't like bringing things up at non-article pages, I wonder if StuRat's dogged insistence that his article serves a purpose not served by the other articles on the subject should be brought up at an etiquette page as the violations listed by Hans.  As an account of Boolean algebra the article is a disaster.  I notice that the many reasons I gave for this a while back have been archived.  Perhaps I should list the main ones here again.   --Vaughan Pratt (talk) 09:13, 16 January 2010 (UTC)
thread_title:  Entire Article Rewrite 

message: hi sorry i don't know where to write this - i edited the "English language" bit re m/f etc, then removed imperative, i think now it is good, i definitely did not hack the page with references to bodily parts. thanks.  —Preceding unsigned comment added by 203.220.104.236 (talk) 08:55, 30 January 2011 (UTC)
thread_title:  A few edits of the "English language"