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Re: Three solution designs to the first three Graphs use cases

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Mon, 30 Jan 2012 20:30:15 +0000
Message-ID: <4F26FDD7.7020707@epimorphics.com>
To: public-rdf-wg@w3.org


On 29/01/12 19:34, Pat Hayes wrote:
>
> On Jan 27, 2012, at 1:13 AM, Andy Seaborne wrote:
>
>>
>>
>> On 27/01/12 03:45, Sandro Hawke wrote:
>>> On Thu, 2012-01-05 at 11:09 +0000, Andy Seaborne wrote:
>>>> - - - - - - - - - -
>>>>
>>>> I find the name TriG/REST confusing because, for me,
>>>> identifying the dereference action is modelling REST which is
>>>> the other
>>>>
>>>> It's more like "TriG/WebCache" -- only one instance of the
>>>> graph containers state is possible.
>>>
>>> I don't follow your logic.   My thinking in picking the name
>>> "TriG/REST" is that the implied relation is the relation that's
>>> kind of at the core of REST, the relationship between a thing and
>>> its 'state'.
>>
>> The difference is time.
>>
>> The relationship of URI to value is time-varying in REST.  RDF does
>> not have that natively so using events (or etc) is a way of having
>> a world model with fixed facts that included time-based actions.
>>
>>>>> g log:semantics { s p o }.       # TriG "REST" semantics
>>
>> But that only works for a single point in time - a single run and
>> observation in cwm.  Indeed, rerun the rules and you may well get a
>> different answer (c.f. tax returns).
>>
>> You can't record that as a fact for a time-varying graph container.
>> You need an indirection though the act of reading the value.
>>
>> Test case - how to say :g was { :s :p :o } at time T1 and { :s :p
>> :z } at time T2.
>
> Right, exactly. This is THE semantic issue here. If we are planning
> to incorporate any kind of state- or time-sensitive meanings into the
> RDF semantics, then the whole RDF model needs to be re-thought from
> the ground up. RIght now, RDF HAS NO NOTION OF STATE OR TIME OR
> CHANGE IN IT ANYWHERE. (Sorry about the shouting, but it is
> apparently needed.)  If we are going to put that idea in, the change
> to RDF will be far more profound and far-reaching than anything we
> have considered so far. The resulting language will not resemble
> current RDF at all at the semantic level. It will no longer mesh with
> OWL or RIF or any of the other formalisms that have been built on it.
> Is this kind of a change within our charter?
>
> Pat

It has always been my assumption that denotation of IRIs is fixed and 
not a time dependent function.

Tagging a graph with the container IRI needs make additional assumptions 
and any use of it needs to be aware of them.

	Andy

>
>
>
>>
>> Andy
>>
>>
>
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Received on Monday, 30 January 2012 20:30:54 GMT

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