- From: Arthur Ryman <arthur.ryman@gmail.com>
- Date: Sat, 26 Sep 2015 08:02:24 -0400
- To: Holger Knublauch <holger@topquadrant.com>
- Cc: "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
Holger, This proposal should replace the current design for sh:qualifiedValueShape, etc. -- Arthur On Fri, Sep 25, 2015 at 11:52 PM, Holger Knublauch <holger@topquadrant.com> wrote: > Would be good to hear from the ShEx camp: > > - Would this feature satisfy your remaining requirements? > - Would we still need sh:qualifiedValueShape then? > > Thanks, > Holger > > > > On 9/26/15 9:13 AM, Arthur Ryman wrote: >> >> I've been following the discussion about repeated properties and >> qualified cardinality constraints, and would like to propose a new >> SHACL language element, sh:partition, that I believe will satisfy the >> requirements. >> >> I the use cases suggest that SHACL needs a way to say that a set of >> nodes must be partitioned into a certain number of disjoint subsets. >> Each subset contains nodes that satisfy certain constraints. Each >> subset must satisfy certain cardinality constraints. >> >> In the case of repeated properties, we are looking at the set of all >> values for a given property (or inverse property) of a given focus >> node. Sets of nodes occur in other contexts and be need to be >> similarly constrained. >> >> It would be a very good thing if a SHACL processor could efficiently >> determine if a given set of nodes could be partitioned according to a >> given partition spec. >> >> SHACL already has sh:minCount and sh:maxCount properties which apply >> to sets of nodes. >> >> SHACL also already has many other properties that define constraints >> on a given node. These are tests or checks that apply to a node and >> are either true or false. Holger listed many of them, e.g. >> - sh:allowedValues >> - sh:class >> - sh:datatype >> - sh:directType >> - sh:minLength >> - sh:maxLength >> - sh:nodeKind >> - sh:maxExclusive etc >> - sh:pattern >> >> I propose to define a new RDF type, sh:QCC for things that specify >> qualified cardinality constraints. However, sh:QCC will normally be >> understood from the context and do not need to appear explicitly in >> the shapes graph. >> >> A sh:QCC may have: >> - zero or one sh:minCount >> - zero or one sh:maxCount >> - zero or more node constraints, for the following list (and possibly >> others that make sense) >> - sh:shape >> - sh:allowedValues >> - sh:class >> - sh:datatype >> - sh:directType >> - sh:minLength >> - sh:maxLength >> - sh:nodeKind >> - sh:maxExclusive etc >> - sh:pattern >> >> A partition is specified by an rdf:List of sh:QCC nodes. Define >> sh:Partition to be this subclass of rdf:List. Again, sh:Partition need >> no appear explicitly. >> A constraint may have zero or more sh:partition properties whose >> values are sh:Partition nodes. All must be satisfied. >> >> The interpretation of a sh:Partition node as a constraint is as follows: >> >> Let the given set of nodes be X. >> Let the sh:Partition node be the list P = (qcc1, qcc2, ..., qccn). >> >> For each qcc in P do the following: >> Let Y be the subset of X that satisfies the node constraints in qcc. >> If Y violates the cardinality constraints of qcc then report a >> violation and break. >> Otherwise remove Y from X and continue. >> End for. >> If X is not empty then report a violation. >> Otherwise report that P is satisfied. >> >> Note that this is a greedy algorithm. Each qcc in the list is matched >> to the fullest extent. Nodes that match one qcc are removed from >> further consideration. Also, the qcc's are checked in the order given >> in the list so there is no combinatorial explosion. >> >> Eric proposed the following example [1]: >> >> <BFPersonInterface1> sh:property [ >> sh:predicate bf:identifiedBy ; sh:pattern "^http://id.loc.gov/" ; >> sh:minCount 1 ; sh:maxCount 1 >> ], [ >> sh:predicate bf:identifiedBy ; sh:pattern "^http://viaf.org/" ; >> sh:minCount 1 >> ] . >> >> In my proposal, this becomes: >> >> <BFPersonInterface1> sh:property [ >> sh:predicate bf:identifiedBy ; >> sh:partition ( >> [sh:pattern "^http://id.loc.gov/" ; sh:minCount 1 ; sh:maxCount >> 1], >> [sh:pattern "^http://viaf.org/" ; sh:minCount 1 ] >> ) . >> >> [1] >> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Sep/0107.html >> >> -- Arthur >> > >
Received on Saturday, 26 September 2015 12:02:52 UTC