- From: Marcelo Arenas <marcelo.arenas1@gmail.com>
- Date: Tue, 16 Mar 2010 11:40:56 +0000
- To: Lee Feigenbaum <lee@thefigtrees.net>
- Cc: Juan Sequeda <juanfederico@gmail.com>, public-rdb2rdf-wg@w3.org
On Tue, Mar 16, 2010 at 2:03 AM, Lee Feigenbaum <lee@thefigtrees.net> wrote:
> On 3/15/2010 11:55 AM, Marcelo Arenas wrote:
>
>>> + the ability to project expressions from queries rather than variables
>>> only
>>
>> I don't understand this functionality. Maybe Lee could gives us an
>> example of such a query.
>
> In SPARQL 1.0, the only thing that can be projected from a query are
> variables:
>
> SELECT ?var1 ?var2 ?var3
> WHERE {
> ... ?var1 ... ?var2 ... ?var3 ...
> }
>
> In SPARQL 1.1, any expression can be projected into a result set:
>
> SELECT ?var1 (?var2 + 2 AS ?sum) (fn:myCrazyFunction(?var3) AS ?crazy)
> WHERE {
> ... ?var1 ... ?var2 ... ?var3 ...
> }
>
> Lee
Thanks for the example, now the functionality is clear. Whether this
is expressible in FOL depends on the functions that are used. For
example, ?var1 + ?var2 AS ?sum is not expressible in FOL if + is not
part of the language; if + is not included as a built-in predicate (or
function) in non-recursive Datalog with safe negation, then the above
functionality of SPARQL 1.1 will not be expressible in the mapping
language.
All the best,
Marcelo
Received on Tuesday, 16 March 2010 11:41:29 UTC