Re: Multisets and 3VL

From: David Fetter <david_at_fetter.org>
Date: Tue, 17 Jan 2006 18:37:35 -0600
Message-ID: <XMOdnbt9oZpSEFDenZ2dnUVZ_sWdnZ2d@speakeasy.net>

vc <boston103_at_hotmail.com> wrote:
>
> David Fetter wrote:

>> Folks,
>>
>> I've read Date, Darwen and Pascal's ideas on how their relational
>> model is based on set theory (I assume they mean ZFC, but it's
>> probably not important) and two-valued logic, and they've done a
>> thorough job of writing this down.
>>
>> Has anybody done similar work starting from multiset theory and
>> three-valued logic?

>
> See:
>
> Query Languages for Bags (1993) Leonid Libkin, Limsoon Wong
>
> Multi-sets and multi-relations in Z with an application to a
> bill-of-materials system (1990)

Thanks :)

> [...]

>> neutral geometry has sharper limits on what it can prove than
>> Euclidean geometry does.

>
> That does not make any obvious sense. What "sharper limits" do you
> have in mind ?

Well, at this stage, it's just fuzzy intuition, but if I had to assign a reason, it would be that I've noticed that when you "know extra stuff" about a problem domain, for example, that every multiset has multiplicity one, or that truth values will only be in {T,F}, you can then use that knowlege to get to places you couldn't have gotten to if you hadn't have it.

Cheers,
David.

-- 
David Fetter david@fetter.org http://fetter.org/
phone: +1 510 893 6100    mobile: +1 415 235 3778

Yesterday, upon the stair,
I saw a man who wasn't there.
He wasn't there again today.
I think he's with the NSA.

Received on Tue Jan 17 2006 - 18:37:35 CST