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Re: Potential text for time-permitting features in F&R

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Thu, 25 Jun 2009 08:36:25 -0400
Message-ID: <4A436F49.3040403@thefigtrees.net>
To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>
Birte, thanks. Sounds good to me.

Lee

Birte Glimm wrote:
> Lee,
> thanks for the work. I would suggest to rephrase OWL dialects into
> profiles because that is the official name used in the OWL 2 spec (I
> guess that is what you mean by dialects) and I would like to mention
> direct semantics here because the RDF semantics of OWL does not really
> need a different entailment regime as I understand it, e.g.:
> 
> [...] Time-permitting, the SPARQL WG will use the existing framework
> to define the semantics of SPARQL queries for one or more of these
> entailment frameworks:
> + OWL 2 with Direct Semantics including OWL 2 profiles
> + RDF Schema
> + RIF rule sets
> 
> Birte
> 
> 2009/6/25 Lee Feigenbaum <lee@thefigtrees.net>:
>> This is to discharge my action at
>> http://www.w3.org/2009/sparql/track/actions/49
>>
>> The goal here is to have enough text that explains what the time permitting
>> features are in a way that:
>>
>> 1) is comprehensive enough to help us build out phase II charter
>> 2) will be re-usable / extendable in future versions of the F&R document
>>
>> To this end, I've tried to do a "Motivation" and brief "Description" for
>> each.
>>
>> Please comment on this, _especially_ if you are not comfortable with any of
>> this for the FPWD. We are _not_ going to spend time on this specific text on
>> Tuesday before deciding to publish a first public working draft unless there
>> are concerns that we have not managed to work out between now and then on
>> the mailing list.
>>
>> Kjetil or Alex, can you please work this into the editor's draft?
>>
>> Also - please note that we may need to refine the description of common
>> functions that is a time-permitting function before publishing the phase ii
>> charter, as per ISSUE-2 (http://www.w3.org/2009/sparql/tracker/issues/2). We
>> can do this following publication of FPWD of F&R.
>>
>>
>> ~~BGP extensions for entailment regimes~~
>>
>> -Motivation-
>>
>> Many software systems that support entailment regimes such as OWL dialects
>> and RDF Schema extend the semantics of SPARQL Basic Graph Pattern matching
>> to apply to entailments other than simple entailment. The formal semantics
>> of these SPARQL/Query extensions are not standardized, and query writers
>> cannot currently be guaranteed interoperable behavior when working with
>> multiple query engines that extend SPARQL with the same entailment regime..
>>
>> -Description-
>>
>> SPARQL/Query 1.0 defines a mechanism to adapt SPARQL to entailment regimes
>> beyond simple entailment by providing necessary conditions on re-defining
>> the meaning of SPARQL Basic Graph Pattern matching. Time-permitting, the
>> SPARQL WG will use the existing framework to define the semantics of SPARQL
>> queries for one or more of these entailment frameworks:
>>  + OWL dialects, including OWL DL
>>  + RDF Schema
>>  + RIF rule sets
>>
>>
>> ~~Property paths~~
>>
>> -Motivation-
>>
>> Many classes of query over RDF graphs require searching data structures that
>> are hierarchical and involve arbitrary-length paths through the graphs.
>> Examples include:
>>
>>  * Retrieving all the elements of an RDF collection (structured as a linked
>> list)
>>  * Retrieve all of the names of people linked to me transitively via the
>> ex:mother and ex:father relationships (i.e. all my known ancestors)
>>  * What are all of the direct and indirect superclasses of a given
>> owl:Class?
>>
>> -Description-
>>
>> SPARQL/Query 1.0 can express queries over fixed-length paths within RDF
>> graphs. SPARQL/Query 1.0 can also express queries over arbitrary but
>> bounded-length paths via repeated UNION constructs. SPARQL/Query 1.0 cannot
>> express queries that require traversing hierarchical structures via
>> unbounded, arbitrary-length paths.
>>
>> Time-permitting, the SPARQL Working Group will define the syntax and
>> semantics of property paths, a mechanism for expressing arbitrary-length
>> paths of predicates within SPARQL triple patterns.
>>
>>
>> ~~Basic Federated Query~~
>>
>> -Motivation-
>>
>> SPARQL is a concise query language to retrieve and join information from
>> multiple RDF graphs via a single query. In many cases, the different RDF
>> graphs are stored behind distinct SPARQL endpoints.
>>
>> -Description-
>>
>> Federated query is the ability to take a query and provide solutions based
>> on information from many different sources. It is a hard problem in its most
>> general form and is the subject of continuing (and continuous) research. A
>> building block is the ability to have one query be able to issue a query on
>> another SPARQL endpoint during query execution.
>>
>> Time-permitting, the SPARQL Working Group will define the syntax and
>> semantics for handling a basic class of federated queries in which the
>> SPARQL endpoints to use in executing portions of the query are explicitly
>> given by the query author.
>>
>>
>> ~~Commonly Used SPARQL Functions~~
>>
>> -Motivation-
>>
>> Many SPARQL implementations support functions beyond those required by the
>> SPARQL/Query 1.0 specification. There is little to no interoperability
>> between the names and semantics of these functions for common tasks such as
>> string manipulation.
>>
>> -Description-
>>
>> Time-permitting, the SPARQL WG will define URIs and semantics for a set of
>> functions commonly supported by existing SPARQL implementations.
>>
>> See Working Group issue: ISSUE-2 -
>> http://www.w3.org/2009/sparql/tracker/issues/2
>>
>>
>> ~~Query language syntax~~
>>
>> -Motivation-
>>
>> Certain limitations of the SPARQL/Query 1.0 language syntax cause
>> unnecessary barriers for learning and using SPARQL.
>>
>> -Description-
>>
>> Time-permitting, the SPARQL Working Group will consider extending
>> SPARQL/Query's syntax to include:
>>  + Commas between variables and expressions within a SELECT list
>>  + IN and BETWEEN operators to abbreviate disjunction and comparisons within
>> FILTER expressions
>>
>>
>> Lee
>>
>>
> 
> 
> 
Received on Thursday, 25 June 2009 12:37:11 GMT

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