Sparql - Applying limiting criteria to predicates

Question

I\'m fairly new to RDF / Sparql, so apologies for any incorrect terminology, and also for the fairly terrible example that follows:

Given the following RDF dataset:<

Answer 1

I don't know the solution in pure SPARQL, sorry. In OpenLink Virtuoso's SPARQL-BI, the solution is this query

prefix e: 
prefix foaf:  
select * 
where
  {
    { select ?orig ?target 
      where
       { ?orig   foaf:knows ?target . 
         ?target a          e:Freemason .
       } 
    } 
    option ( TRANSITIVE, 
             T_IN(?orig), 
             T_OUT(?target), 
             T_DISTINCT, 
             T_MIN(1)
           )
    filter ( ?orig =  )
  }

-- with these results --

orig                               target