# filename: ex507.rq

PREFIX ab: <http://learningsparql.com/ns/addressbook#> 

SELECT ?craigEmail ?craigTelephone
WHERE
{
  ?person ab:firstName "Craig" . 
  ?person ab:email ?craigEmail . 
  OPTIONAL { ?person ab:homeTel ?craigTelephone }
  FILTER(regex(?craigEmail,"yahoo"))
}