Recursive concise bounded description

cbd.rq

# SPARQL 1.1 implementation of concise bounded description (<https://www.w3.org/Submission/CBD>).

PREFIX :    <http://example.com/>
PREFIX non: <http://non/>

CONSTRUCT {
  :resource ?p1 ?r1 .
  ?r2 ?p2 ?r3 .
}
WHERE {
  # :resource is the IRI of the resource we want to describe.
  :resource ?p1 ?r1 .
  OPTIONAL {
    # Since variables cannot be used in SPARQL 1.1 property paths
    # we can ask for any but a (presumably) non-existent property.
    # We use zero or more quantifier (i.e. "*") to recursively
    # expand to blank node neighbourhood.
    ?r1 (!non:existent)* ?r2 .
    FILTER (isBlank(?r1) && isBlank(?r2))
    ?r2 ?p2 ?r3 .
  }
}

example.ttl

@prefix :     <http://example.com/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

:resource a :C ;
  :p1 [
    a :D ;
    :p2 [
      a :E
    ]
  ] .

:C a rdfs:Class .
:D a rdfs:Class .
:E a rdfs:Class .

We plan to use PATH for that but from what I know we cannot use it in sub-selects right now