- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: Thu, 25 Jun 2009 08:36:25 -0400
- 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 UTC