Re: First order logic and SPARQL

Bob --

+1 vote for that, but why rule out recursion?

                                -- Adrian

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Adrian Walker
Reengineering

On Mon, Sep 6, 2010 at 3:21 PM, Bob MacGregor <bob.macgregor@gmail.com>wrote:

> I would say that the mindset "NAF is not appropriate for SPARQL" is a piece
> of the explanation for the
> glacial pace of adoption of Semantic Web technology in commercial
> settings.  If indeed SPARQL is
> supposed to be religiously open-world (I'm not saying I agree), then IMO
> that strengthens the argument for
> the adoption of a second RDF language, e.g., something like non-recursive
> Datalog with negation, that
> is more practical/useful.
>
> Bob
>
>
> On Sun, Sep 5, 2010 at 11:54 PM, Pat Hayes <phayes@ihmc.us> wrote:
>
>>
>> On Sep 6, 2010, at 12:13 AM, Bob MacGregor wrote:
>>
>> Hi Pat,
>>
>> On Sun, Sep 5, 2010 at 6:31 PM, Pat Hayes <phayes@ihmc.us> wrote:
>>
>> On Sep 5, 2010, at 4:48 PM, Bob MacGregor wrote:
>>
>> > My personal interest is in a query language for RDF that's easy to use,
>> and, among other things,
>> > has a negation operator that is intuitive.
>>
>> Id be interested to know what you consider to be intuitive here. Is
>> negation by failure intuitive for most Web sources? Do you routinely
>> conclude, from a failure to find a sentence asserted on a website, that it
>> is false?
>>
>> Fundamental to your argument seems to be "sentence asserted on a
>> website".   If I grabbed
>> triples from some random Website, I might not be confident in using NAF.
>> But I don't do that.  I work
>> with graphs that I've built from sources I trust, and I know which parts
>> of the graph are expected to
>> be complete, and NAF is perfect for those parts.
>>
>>
>> Well, bully for you, but SPARQL is supposed to be a standard for use with
>> RDF on the Web. These nice assumptions of completeness just where you expect
>> it cannot be sustained in the wider world of RDF data, and there is no way
>> to transmit them (the assumptions) even when they are correct. So NAF is not
>> appropriate for SPARQL.
>>
>> Pat
>>
>>
>> - Bob
>>
>>
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>>
>>
>
>
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> Robert MacGregor
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