Talk:Three-valued logic

message: RJFJR 22:26, Feb 5, 2005 (UTC)
What is "attention"? --Loqi T. 05:38, 11 October 2006 (UTC)
thread_title: Does attention belong on talk or article page?

message: The intro currently says that ternary logic is a multi-valued logic.  But the article is kind of reluctant to say exactly how to implement ternary logic (such as saying that the assignment of ternary values to truth values is or a permutation).  Does that mean this is really a description of many different logics?
Am I splitting semantic hairs again? RJFJR 22:24, Feb 5, 2005 (UTC)
c:No, you're absolutely right, ternary logic is a collective name for a wide variety of logics. Qwertyus 13:19, 16 August 2005 (UTC)
replies: text: There are a number of Ternary logics.  The article provides a truth table for ONE of them (Admitedly a common one).  The article's underlying assumption is that the third value is "unknown".  There are different ternary logics with different truth tables that coorespond to other assumed meanings.   Which is the "correct" truth table is still a matter of debate.  (Particularly when adding modal operators to the ternary logic). Nahaj 15:35, 17 January 2006 (UTC)
thread_title: Is this article defining 'a' logic or a 'class' of logics?

message: I find the use of 0,1,2 rather confusing. Why not use *, T and F ? --Tillmo 15:42, 24 March 2006 (UTC)
replies: text: I agree.  Also, I think that the conjunctions would be easier to see if they were separated each into their own table. Smmurphy(Talk) 21:54, 2 June 2006 (UTC)

text: I don't think it needs to be split into separate truth tables, but the values certainly need to be clarified, since (even if we're sticking to one class of ternary logic) different sources will attribute different values to 0, 1, and 2.--Rinn 16:39, 15 July 2006 (UTC)

text: Yes, I've addressed this with a discussion per the truth tables derived from Kleene 1952 (see entry below). Bill Wvbailey (talk) 23:52, 6 April 2011 (UTC)
thread_title:  Why numbers? 

message: I believe there should be a discussion of the different truth valuation functions. Definitely Strong vs. Weak Kleene logic should be addressed here. I know this is addressed slightly in George Boole's "Logical Options" to some extent, and the discussion must be carried on further elsewhere.
:Yes, I've addressed this with a discussion per the truth tables derived from Kleene 1952 (see entry below). Bill Wvbailey (talk) 23:52, 6 April 2011 (UTC)
thread_title: Truth Valuation Functions

message: I would think that something like -, 0 and + would psychologically be the most satisfying choice to represent the different truth values. Does anyone agree? -- Dissident (Talk) 03:13, 25 August 2006 (UTC)
replies: text: I disagree on the grounds that 0 is usually associated with false, thus possibly causing confusion between your - and 0. I agree with someone above who suggested that F, *, and T are good choices. Or perhaps 0, 1/2, and 1. I do agree that the current 0, 1, 2 notation is very confusing. --216.254.66.59 23:47, 28 August 2006 (UTC)
replies: text: Is there any fixed usage by major journals?  in the most popular textbooks? Smmurphy(Talk) 02:10, 5 October 2006 (UTC)

text: * I don't think there's a standard numerical notation accepted by everyone. { -1, 0, +1 } is preferred for digital hardware. { 0, ½, 1 } is popular with some, and I don't know who came up with { 2, 0, 1 } but I've seen it in more than one place. Using spelled-out words has the additional minor controversy of what word to use for the neither-true-nor-false value. I've seen unknown, maybe, possible, indeterminate, inconclusive, uncollapsed and fictive. I'd go with unknown or possible. --Loqi T. 01:51, 11 October 2006 (UTC)
replies: text: This probably wouldn't be appropriate since I haven't seen it in use elsewhere, but in my own tinkering I have found { -, *, + } to be the most intuitive.  It eliminates the confusion of 0 being misinterpreted as False, and * is also commonly used as a wildcard for "anything" or "unknown". Maghnus 09:05, 19 March 2007 (UTC)
thread_title:  Choice of symbols 

message: I’d like to see a section on motivations for three-valued logic (future contingents, quantum mechanics, intuitionism in mathematics, etc.), and then a section on different systems (Strong and Weak Kleene, Sobocinski, Reichenbach, etc.) There should be a brief discussion, at the end, of truth-functional completeness, including mention of Sheffer connectives. If no one objects, I’ll pull this together, incorporating as much previously posted material as I can, and heeding the above comments where possible. I'll cite books by Susan Haack and Nicholas Rescher as primary sources. Comments? --Knorlin 10:50, 25 November 2006
:Sounds like a good plan. What about Łukasiewicz, though? An article on trivalent logic seems to be sorrowfully incomplete without mention of him and his work. Simões (talk/contribs) 19:51, 25 November 2006 (UTC)
replies: text: That's reasonable. I look forward to seeing how it turns out! Simões (talk/contribs) 23:12, 25 November 2006 (UTC)
thread_title:  Proposed revamp 

message: Knorlin has offered to do a load of work offline on a new version of the article, but it's been a while since the article has been cut down. I'd like to see some progress, and there seems to be interest by a few people in collaborating on it.
I've created a page for this collaboration: Talk:Ternary_logic/Draft It's intended as a back-end workspace for the new version of the article, so please use it in place of the live page to develop the article until this sourcing controversy is ironed out.
In the meantime, I, for one, would rather have the long, unsourced version, rather than the short, uninformative version as the live article. --Loqi T. 20:22, 25 December 2006 (UTC)
thread_title:  Draft workspace for new version. 

message: Changed the word "triggers" to "initiates an action" to avoid possible confusion with actual SQL Triggers.  Also added that while Unknown and False truth values cause DML statements to disregard rows, only a False truth value will cause a row to fail the validation of a SQL Check Constraint.  Both True and Unknown indicate a valid row as far as a SQL Check Constraint is concerned.  Info was added to the "Ternary logic in database applications" section.  The Null article also provides a more in-depth discussion of SQL's implementation of three-valued logic, so I'm adding a link to that article as well.SqlPac 14:52, 17 April 2007 (UTC)
replies: text: Oops, I was so wrapped up in "triggers" I initially put trigger in there - corrected to Check Constraints.SqlPac 15:09, 17 April 2007 (UTC)
thread_title: Added slight clarification of SQL 3VL

message: This statement was included in the section on SQL 3VL:
::Comparing anything to NULL—even another NULL—results in an UNKNOWN truth state (which happens to also be represented by a NULL value).
(Emphasis added by me).
If "NULL=UNKNOWN", then a choice needs to be made to change the 3VL truth table (or not) to reconcile the fact that SQL NULLs propagate through expressions (a basic property of NULL):
Standard SQL 3VL truth table:
 ( TRUE OR UNKNOWN ) → TRUE
 ( FALSE AND UNKNOWN ) → FALSE
"NULL=UNKNOWN" SQL 3VL truth table:
 ( TRUE OR NULL ) → NULL ( = UNKNOWN )
 ( FALSE AND NULL ) → NULL ( = UNKNOWN )
If NULL = UNKNOWN then the result of ( TRUE OR NULL ) is not TRUE as stated in this article, but rather it is UNKNOWN.  In SQL, an easier way to think of it is that NULL is a "placeholder" that represents a missing value.  UNKNOWN represents the result of any comparison to a missing value.
(NULL is also not a "value", it's the absence of a value, but we'll save that discussion for another day).
:::Good call on removing that parenthetical. Not only was it inaccurate, but also irrelevant and confusing. ==Loqi T. (talk) 20:57, 27 February 2008 (UTC)
thread_title: Changed False Statement

message: The article referenced provides no relevant information, other than the one sentence statement that it uses three valued logic.  (I.E. going to the page doesn't gain you any information.) And that statment there has the complaint that there is no citation.  And I can't find any article on the language that makes the claim.  So, since seeing that also provides no information, I removed it. 155.101.224.65 (talk) 16:10, 7 April 2008 (UTC)
thread_title:  Removed reference to Aymara language from "See also" 

message: The author claims that the Electronics is four- and more- valued. Ok, he has missed the topic. I would also like to ask the author to refer us to the standard that assigns the four values for the electronics simulation. The section must be removed as a mistake. --Javalenok (talk) 19:44, 10 September 2009 (UTC)
thread_title:  The section on Electronics? 

message: The intent here is to get some tables or images that compare the three logics succinctly, because right now the article is of no help whatever. (And By the way, the Łukasiewicz article is opaque, and functionally useless. There must be a better way to present it). The following is derived from Kleene 1952:
As noted here, the tables are blurry because they're pngs that are reduced in resolution. I can do these crudely in tables (see Principle of bivalence for an example of my handiwork), but to do them nicely so that they're easy to interpret and actually look like truth tables is a trauma, been there, tried it  . . .. The following is what I want the tables to look like:
I could create one for the SQL logic, too. I could move a table to each logic, but what's important is to get them all in one place and into a common format. Any thoughts out there before I plunge ahead? 
At this point I am a bit confused by Kleene's use of ≅ and ≡, and I need to verify the formulas where ≅ is used, so the above will be emeneded as I make progress. Note Kleene's interesting example of the failure of the LoEM: Q & (R V ¬R) ≅ Q. Bill Wvbailey (talk) 17:43, 6 April 2011 (UTC)
thread_title:  Truth table images, Kleene and Lukasiewicz logic, SQL 

message: Why are there exactly 3072 such logics?  — Preceding unsigned comment added by 85.64.57.89 (talk) 11:11, 25 February 2013 (UTC)
thread_title:  3072 such logics 

message: User 103.21.126.45 
(talk)
changed the crystal clear (although perhaps inelegant) table
:
A      	B      	A and B	A or B
False  	False  	False  	False
False  	Unknown	False  	Unknown
False  	True   	False  	True
Unknown	False  	False  	Unknown
Unknown	Unknown	Unknown	Unknown
Unknown	True   	Unknown	True
True   	False  	False  	True
True   	Unknown	Unknown	True
True   	True   	True   	True
into
:
AND    	True   	False	Unknown
True   	True   	False	Unknown
False  	False  	False	False
Unknown	Unknown	False	Unknown
:
OR     	True	False  	Unknown
True   	True	True   	True
False  	True	False  	Unknown
Unknown	True	Unknown	Unknown
but, unfortunately, provided no explanation for how to interpret the new tables, so the change is pedagogically insensitive to readers who may not know how to read them.  What are the rows?  The columns?  What do the interior elements of the matrix represent?  Those headers were useful and shouldn't be omitted for the sake of style.  I propose to change it back to the prevision exposition that spelled out the truth values in a way that most everyone will understand.
Scwarebang (talk) 10:02, 20 August 2013 (UTC)
replies: text: I find the two-dimensional matrices much easier to comprehend, as they allow to see patterns in the assignment of truth values for the connectives, whereas the linearized versions read like unstructured line noise. But then again I’m a logician, so I can’t tell what is better for the uninitiated.—Emil J. 11:17, 20 August 2013 (UTC)
replies: text: I like the new ones better too as they separate the connectives into different tables. Both styles are used in logic textbooks, so which one is clearer for newbies will depend on which textbook you've read. QVVERTYVS (hm?) 11:34, 20 August 2013 (UTC)
replies: text: I added more explicit headers to the tables to alleviate Scwarebang’s concern about missing information.—Emil J. 12:14, 20 August 2013 (UTC)
thread_title:  The new truth tables are needlessly opaque for neophytes 

message: Reference 9, "http://www.aymara.org/arpasi-idioma-aymara.html" isn't in English.  I'm not sure what language it is in.  Can someone recognize it with confidence and mark it?  RJFJR (talk) 13:54, 20 August 2013 (UTC)
replies: text: It’s just Spanish.—Emil J. 14:32, 20 August 2013 (UTC)
replies: text: Thank you.  RJFJR (talk) 17:02, 21 August 2013 (UTC)
thread_title:  non English ext link, which language? 

message: The current text says that SQL is based on K3, and K3 and L3 differ with respect to {A AND B} and {A OR B} which are said to yield UNKNOWN in K3 and TRUE and FALSE in K3 when A and B are both UNKNOWN. However, K3 and L3 do have the very same truth tables for AND and OR (as stated previously in the article). This can't be right.
--77.185.171.151 (talk) 16:06, 26 February 2014 (UTC)
thread_title:  SQL and L3 

message: Dear editors, the truth tables of material and Łukasiewicz implications are written in the T-U-F -order, while before it was written in the F-U-T order. Could you synchronize these? It took me some time to figure out why do I have a different table for the material implication... Thanks!188.36.216.64 (talk) 15:34, 4 November 2014 (UTC)
thread_title: Confusing truth tables

message: I haven't seen it directly mentioned on this page yet, but it seems like the article aught to mention that many (if not most) programming languages contain trinary boolean systems (yes I know how stupid that term sounds). In every language I've used, there is some way of declaring a boolean variable with a value of true, false, or null, thereby making their binary boolean systems trinary.
Should this be in the article in some form? Is it, and I've just missed it?
142.156.1.225 (talk) 15:07, 15 October 2018 (UTC)
thread_title:  Has this come up yet? 

message: Since Pierce was unpublished, and since Łukasiewicz published extensively on this over decades, ca. 1920-1949, it is strange to include in the introduction a mention of Pierce whose work was unknown until the 1960's. Massive numbers of papers were published on non-binary logic prior to the discovery of the unpublished work of Pierce.  I moved this information to its own subsection. It is interesting, but unpublished work does not give you priority of invention. It only demonstrates that the state-of-the-art was close to this discovery. Nick Beeson (talk) 12:37, 29 March 2021 (UTC)
thread_title:  Pierce 

message: Assuming the 3VL is the one that SQL uses, it seems that DM's laws apply ("A ∧ B = ¬(¬A ∨ ¬ B)" is shown in  https://en.wikipedia.org/wiki/Three-valued_logic#%C5%81ukasiewicz_logic so it sort-of applies) but a clear statement would be good 89.241.103.187 (talk) 15:06, 25 March 2022 (UTC)
thread_title:  De Morgan's laws + 3VLs