Re: Codd and many-valued logics
Date: Sun, 5 Jun 2016 13:03:36 +0200
Message-ID: <nj10u8$ftt$1_at_adenine.netfront.net>
On 2016-06-05 02:44:56 +0000, compdb_at_hotmail.com said:
> On Monday, May 30, 2016 at 6:48:00 AM UTC-7, Nicola wrote:
>> It seems to me that Codd never referenced the literature on many-valued >> logics in his papers (I'd be glad to be proven wrong). Do you have any >> idea why?
>
> In his Version 2 book REFERENCES intro:
>
> Several texts dealing with predicate logic also appear in the reference
> list. In descending order of difficulty, they are as follows: (Church 1958),
> (Suppes 1967), (Exner and Rosskopf 1959), (Stoll 1961), and (Pospesel
> 1976).
>
> The texts appear in the references list that follows. They are
> referenced in the text. But only in a general way. From the section
> Power of the Relational Language:
>
> Excluding consideration of general logical inference, RL as a language
> has the full power of four-valued, first-order predicate logic
> [Pospesel 1976, Stoll 1961, Suppes 1967, Church 1958].
As far as I can tell, none of those references deals with many-valued logics. Which looks quite strange in a sentence that explicitly mentions 4VL. No mention of Ackermann 1967, Rescher 1969, Rosser&Turquette 1952.
> (Although this is odd because without logical inference it's a bit much
> to claim that one has a logic let alone the "full power" of one with it.
But at least there is potential for adding inferential power, witness Datalog.
> I don't know Codd's reasons for the nature of his references to logic.
>
> But the little of logic that he used hardly needs references.
>
> Ie a few truth tables. Eg for AND, OR, NOT & IS NULL in 3VL.
Sure, Codd's treatment is self-contained. But since the role of
classical predicate calculus is (rightly) emphasized so much, why not
emphasize connections with existing many-valued formalisms? Maybe,
because the foundations are not as strong?
> There isn't much else that's "logical" about his use of MVLs. I don't
> know what you would expect to find of use in a reference.
The "shoulders of giants" upon which everyone builds upon.
Nicola
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