OpenLink Virtuoso: Finding if two nodes are connected within a certain distance

Question

Hi folks,

How can I find the distance between 2 nodes in a graph using Virtuoso? I've read the Transitivity documentations but they limit you to one predicate e.g.:

SELECT ?link ?g ?step ?path
WHERE
{
  {
    SELECT ?s ?o ?g
    WHERE
      {
        graph ?g {?s foaf:knows ?o }
      }
  } OPTION (TRANSITIVE, t_distinct, t_in(?s), t_out(?o), t_no_cycles, T_shortest_only,
  t_step (?s) as ?link, t_step ('path_id') as ?path, t_step ('step_no') as ?step, t_direction 3) .
  FILTER (?s= <http://www.w3.org/People/Berners-Lee/card#i&gt;
  && ?o = <http://www.advogato.org/person/mparaz/foaf.rdf#me&gt;)
}
LIMIT 20

Only traverses foaf:knows and not any predicate type. How can I extend this to 'whatever predicate'? I don't need the actual path, just a true/false (ASK query). Changing the foaf:knows to ?p seems like an overkill.

I'm currently performing a set of recursive ASKs to find out if two nodes are connected within a specific distance but that doesn't seem efficient.

Answer 1

Hi Paras,

You should be able to use p instead of foaf:knows in your query to determine if there's a path between the nodes ie

`SELECT ?link ?g ?step ?path
   WHERE
   {
     {
       SELECT ?s ?o ?g
       WHERE
         {
           graph ?g {?s ?p ?o }
         }
     } OPTION (TRANSITIVE, t_distinct, t_in(?s), t_out(?o), t_no_cycles, T_shortest_only,
     t_step (?s) as ?link, t_step ('path_id') as ?path, t_step ('step_no') as ?step, t_direction 3) .
     FILTER (?s= <http://www.w3.org/People/Berners-Lee/card#i&gt;
     && ?o = <http://www.advogato.org/person/mparaz/foaf.rdf#me&gt;)
   }
   LIMIT 20`

Best Regards

Hugh Williams

OpenLink Software