- From: Harry Halpin <hhalpin@w3.org>
- Date: Wed, 19 Jan 2011 12:22:41 -0000 (GMT)
- To: "Ivan Herman" <ivan@w3.org>
- Cc: "Alexandre Bertails" <bertails@w3.org>, "Juan Sequeda" <juanfederico@gmail.com>, "RDB2RDF WG" <public-rdb2rdf-wg@w3.org>
>
> On Jan 18, 2011, at 19:05 , Alexandre Bertails wrote:
> [snip]
>>
>> Juan, in order to help you with your action, I would like you to
>> considerer the following:
>>
>> [[
>> CREATE TABLE Debts (
>> Name varchar(50),
>> Amount Integer
>> );
>> INSERT INTO Debts (Name, Amount) VALUES("juan", 50);
>> INSERT INTO Debts (Name, Amount) VALUES("juan", 50);
>> ]]
>>
>> Using this very simple RDB [1] example, can you go through all the
>> phases that lead to the RDF where I owe you 100?
>
>
> Alex, for my understanding: what I would expect to see in RDF are two
> pairs of identical triples with different subjects. How would a direct
> produce anything whereby I owe Juan 100? I will owe 50 twice, but the fact
> that this is a hundred is a step that the RDF per se cannot say...
Otherwise known as "RDF can't add, and (up until recently) neither can
SPARQL". Which is a feature, not a bug, re decidability :)
However, I'm assuming Alex is asking with Datalog semantics, do you get
with those two insert statements *two* distinct pairs of triples
(multiset) or just one (set)?
Multisets have repeated membership, while sets don't I think.
>
> Ivan
>
>
>
>
>
>>
>> Alexandre.
>>
>> [1] http://www.w3.org/TR/2010/WD-rdb-direct-mapping-20101118/#Rel
>>
>>
>
>
> ----
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> PGP Key: http://www.ivan-herman.net/pgpkey.html
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>
>
>
>
>
>
Received on Wednesday, 19 January 2011 12:22:46 UTC