Hi Andy, Below, a first draft how a SPARQL command can be defined in a Jena rule. In example 1) is defined that a given student is diligent in a given class if he doesn't fail more than 1 lesson of that class. As this command has an aggregate clause, in the best of my knowledge I can’t express the same thing with owl or rules. In a same situation that I have in a project that i’m developing, I bypassed using the clause "construct" and load the result to the data repository. However, I cannot do this with dynamic data.
Example 2) and example 3) I took from http://spinrdf.org/. I know that i can do the same thing using rules. However, SPARQL is a very expressive command and there are several situations that we can better express in SPARQL than in rules. Example 1) A given student is diligent in a given class if he doesn't fail more than 1 lesson of that class. prefix exa: <http://www.example.org/example#> (?s ex:isDiligent ?c) <- (select ?s ?c where { ?s exa:enroledAt ?c . MINUS { select ?s ?c { select ?s ?c (count(1) AS ?nc) where { ?s exa:failsTo ?l . ?l exa:isLessonOf ?c . } group by ?s ?c having (?nc >= 2) } } }). Example 2: A rectangle is square if the width is equal to the height. (?r rdf:type ex:Square) <- (select ?r where { ?r ex:width ?width . ?r ex:height ?height . FILTER(?width != ?height) . }). Example 3: The area of a rectangle is the product between the width and the height. (?r ex:area ?area) <- unbound(?area), (select ?r ?area where { ?r ex:width ?width . ?r ex:height ?height . bind( ?width * ?height as ?area ) . }). (?r ex:area ?area) <- bound(?area), (select ?r ?area where { ?r ex:width ?width . ?r ex:height ?height . bind( ?width * ?height as ?a ) . FILTER (?a = ?area) . }). Miguel On 05/03/14 08:03, "Andy Seaborne" <a...@apache.org> wrote: >Hi Miguel, > >So that we know we're talking about the same thing, do you have some >concrete examples of what the SPARQL commands would look like? > >This isn't to fix the design in anyway, just to have an illustration of >the ideas for the moment. > > Andy > >On 04/03/14 18:18, Miguel Bento Alves wrote: >> Dear all, >> >> I¹m Miguel Bento Alves, I¹m a Phd student in New University of Lisbon. I >> want to develop the project described below, that was proposed by >>myself, >> in Google Summer code 2014. I need a mentor with knowledge about how >>Jena >> is implemented to give me the guidelines to implement the project and >> supervised my implementation. >> >> Best regards, Miguel Bento Alves >> >> On 04/03/14 18:09, "Miguel Bento Alves (JIRA)" <j...@apache.org> wrote: >> >>> Miguel Bento Alves created JENA-650: >>> --------------------------------------- >>> >>> Summary: Define SPARQL commands in Jena rules >>> Key: JENA-650 >>> URL: https://issues.apache.org/jira/browse/JENA-650 >>> Project: Apache Jena >>> Issue Type: New Feature >>> Reporter: Miguel Bento Alves >>> >>> >>> The goal of this project is allow the definition of SPARQL commands in >>> Jena rules. Thus, we increase the expressiveness of Jena. Something >>>look >>> alike is spin-rules, where SPIN means SPARQL Inferencing Notation, a >>> SPARQL-based rule [1][2]. However, the purpose is not to implement SPIN >>> in Jena but provide Jena with the mechanisms to take the same >>> expressiveness as the spin frameworks. >>> >>> The main tasks of this project are: >>> 1. Defining how a SPARQL command can be declared in a rule. This task >>> encompass the discussion with the Jena community. >>> 2. Provide Jena with the mechanisms defined in 1. >>> >>> [1] http://www.w3.org/Submission/2011/SUBM-spin-overview-20110222/ >>> [2] http://www.w3.org/Submission/2011/SUBM-spin-sparql-20110222/ >>> >>> >>> >>> -- >>> This message was sent by Atlassian JIRA >>> (v6.2#6252) >> >> >
