Re: Codd and many-valued logics

On Sunday, June 5, 2016 at 4:03:38 AM UTC-7, Nicola wrote:
> On 2016-06-05 02:44:56 +0000, com..._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?

>> 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.

Datalog adds inferential power to Codd-style DBMSs. But it is entirely 2VL. It relies on what is not derivable being taken as false.

>> But the little of logic that he used hardly needs references.

> 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?

Because the connections are trivial (my last quoted sentence) and Codd's system is not useful (my next quoted sentence).

> Maybe, because the foundations are not as strong?

Don't understand.

>> 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.

I don't understand what you are trying to say, could you clarify? No standing on shoulders was done by Codd re applying higher level logics to the relational model.

philip Received on Sun Jun 12 2016 - 10:24:16 CEST