anchor.diff:  Performace suggests how powerful the endpoint is.
   
   We measure the response times of the two queries, Listing
  -<<query_ask, 14>>, <<query_for_list_of_graphs, 15>>. The former query is a
  +<<query_ask, 23>>, <<query_for_list_of_graphs, 24>>. The former query is a
   most simple query and we use this query to estimate the transfer time.
   The latter query requires a little computations for endpoints. We
   believe the execution cost of this query does not differ very much
   according to the size of data.
   
   [[query_ask]]
  -.Listing 14. A Most Simple Query
  +.Listing 23. A Most Simple Query
   ....
   ASK {}
   
   ....
   
   [[query_for_list_of_graphs]]
  -.Listing 15. A Query for Listing Graphs
  +.Listing 24. A Query for Listing Graphs
   ....
   SELECT DISTINCT
     ?g
  
positive.code:   [] ?p ?o.
    FILTER(isLiteral(?o))
  }
  
  ....
  4.  Properties
  +
  If there is GRAPH clause being applied, we retrieve a list of properties using a query described in Listing
  <<query_for_properties_on_a_graph, 9>>.
  +
  [[query_for_properties_on_a_graph]]
  .Listing 9. Obtain the properties on a graph g
  ....
  SELECT DISTINCT ?p
          FROM <g>
  WHERE{
          ?s ?p ?o.
  }
  
  ....
  +
  We evaluate Metadata score as follows:
  
negative.code:   GRAPH ?g { ?s owl:sameAs ?o } .
  }
  LIMIT 1
  ....
  +
  [[query_for_see_also_on_a_graph]]
  .Listing 20. A Query for a See Also Statement on a graph g
  ....
  PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
  SELECT
  *
  WHERE {
  GRAPH ?g { ?s rdfs:seeAlso ?o } .
  }
  LIMIT 1
  ....
  +
  [[query_for_same_as_on_background_graph]]
  .Listing 21. A Query for a Same AS Statement on the background graph
  ....
  PREFIX owl:<http://www.w3.org/2002/07/owl#>
  SELECT
    *
  WHERE {
    ?s owl:sameAs ?o .
  }
  LIMIT 1
  ....
  +
  [[query_for_see_also_on_background_graph]]
  .Listing 22. A Query for a See Also Statement on the background graph
  ....
  PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
  SELECT
  *
  WHERE {
    ?s rdfs:seeAlso ?o .
  }
  LIMIT 1
  ....
  
  +
  Linked Data Score is a percentage of the satisfied rules.
  
  