comp.databases.theory Google Group

Re: teaching relational basics to people, questions

2009-12-18T08:23:54Z

Can I ask whether your question has been answered yet? I'm a bit
puzzled by it because this is basically a mathematical theorem and as
such the answer to it lies in understanding the math. But in your
additional text you seem to question more the philosophical /
intuitive foundations of these notions. Is that correct? And what is

Re: Fitch's paradox and OWA

2009-12-18T00:40:05Z

Your addition of 'now' to (NonO) is the cause of your confusion. Go back
and re-read what you cited.
If K is the epistemic operator meaning 'it is known by someone at some time
that,' then not K would have to deny that, meaning 'it is not known by
anyone at any time that,' so with that in mind....

Re: Fitch's paradox and OWA

2009-12-17T22:52:46Z

I don't understand the paradox.
[link]
explains:
suppose that
(KP) all truths are knowable, i.e. can be known by somebody at some time
and
(NonO) not all truths are known now
then
(1) there is an unknown truth p
and then
(2) p is true and unknown is itself a truth

Re: Fitch's paradox and OWA

2009-12-17T18:55:08Z

Good point. I'm not sure that's what I want to say, either. I'll
give it some more thought.

Re: What would be a truly relational operating system ?

2009-12-17T16:10:57Z

This is an interesting idea.
I don't know about making an os really relational.
However, it can still be a databased oriented or driven os.
For example, registry from windows, configuration files, and other os
files, could be xml.
I really mean a xml database oriented and driven operating system.
Xml files can store encrypted or ciphered data without problems (this

Call for Papers & Sessions: The 2010 International Conference on Software Engineering Research and Practice (SERP'10), USA, July 2010

2009-12-17T15:58:01Z

It would be greatly appreciated if this announcement could be
shared with individuals whose research interests include
software engineering research and practice. Thanks.
-------
CALL FOR PAPERS
and
Call For Workshop/Session Proposals

Re: Fitch's paradox and OWA

2009-12-17T14:51:36Z

Which in my world view it is. It's positively weird to say that
Fermat's last theorem was not true until a proof was found. If you
want to do so, be my guest, but I'd argue you would be using another
definition of truth than I am.
-- Jan Hidders

Re: Fitch's paradox and OWA

2009-12-17T09:22:09Z

A relation with no attributes is a simple proposition, so you're
saying the chosen assumption is a value in the db, right? I prefer
this, although TTM states they subscribe to CWA.
Is it necessarily a db-wide choice, or could it be useful to
distinguish the choice per relation?

Re: Fitch's paradox and OWA

2009-12-17T03:06:42Z

To be more clear/blunt, in the context of the RM, D&D have it that it is
a value of the relation that has no attributes. This may seem obscure
in general language, but in the db machine context it is much
simpler/clearer than the above.

Re: Fitch's paradox and OWA

2009-12-17T02:56:14Z

"All truths are known" is only problematic if you assume that truth
exists independent of cognition. From a phenomenalistic point of
view, both entities and predicates exist purely in the mind, which
means that all truths are known, but doesn't exclude the possibility
of creating new truths based on sense data. I'm currently leaning in

Re: Fitch's paradox and OWA

2009-12-17T01:23:34Z

On Wed, 16 Dec 2009 13:09:42 -0800 (PST), Jan Hidders
A segue to the continuum hypothesis?
Sincerely,
Gene Wirchenko

Re: Making Count(*) return zero

2009-12-16T21:56:59Z

On Dec 11, 6:05 pm, Hugo Kornelis
Actually, SS2K8 does now include support for the syntax, FWIW:
SELECT ID
FROM (VALUES(51),(53),(55)) AS Foo(ID)
Take Care,
TroyK

Re: Fitch's paradox and OWA

2009-12-16T18:48:20Z

I had never heard of Fitch's paradox, but it sounds a like Gödel has
disproved it somewhat with his theorem.
Gödel theorem proves that in any system of sufficient reasoning power,
there are truths about the system which can not be derived from within
the system. There is no contradiction, unless your truths somehow

Re: Fitch's paradox and OWA

2009-12-16T21:41:22Z

Heh... not to mention vice-versa, the chronic slant of so many!

Re: Fitch's paradox and OWA

2009-12-16T21:09:42Z

Only if you assume that the database contains everything that is
known. It rarely does. :-)
Besides, do you really believe that everything that is true can be
known? ;-)
-- Jan Hidders