PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX fn: <http://www.w3.org/2005/xpath-functions#>
SELECT DISTINCT *
WHERE {
  ?a ?b ?c.
  FILTER(?a = fn:abs(?b))
  FILTER(?a = fn:floor("string literal"))
  FILTER(?a = fn:ceiling(?b))
  FILTER(?a = fn:round(?b))
  FILTER(?a = fn:string-length(?b))
  FILTER(?a = fn:concat(?a, ?b, ?c))
  FILTER(?a = fn:concat())
}
