Select more

Approximate search that relax type constraints and return best approximations of the query. Syntactically, the more keyword in the select clause of a Corese query asks for approximate answers. In this case, Corese basically approximates every concepts of the query.

select more where

However, its query language allows to require the specialization of some concepts while approximating the others by using type comparators. (see section on type comparators below) For instance, by using the <=: operator, Corese is able to retrieve the persons interested in Knowledge Engineering (or something close) and member of a project (or something close) by processing the following query :

  select more where
  ?person c:interestedBy ?k
  ?person <=: c:Person
  ?k rdf:type c:KnowledgeEngineering
  ?person c:member ?project
  ?project rdf:type c:Project

In this query, the class Person or one of its subclasses is required by using the <=: specialization operator, while KnowledgeEnginering and Project may be approximated.

It is possible to limit the number of approximate answers computed by the engine in order to withdraw those that are considered to be less interesting than the best results already found. For this purpose, it is possible to specify a relative threshold over which bad answers are rejected. More precisely, answers are rejected if their distance multiplied by the threshold is greater than the best known answer.

select threshold 2 where