PREFIX  xsd:    <http://www.w3.org/2001/XMLSchema#>
PREFIX ex: <negation/temporal-exclusion#>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
# The closest pre-operative physical examination
SELECT ?exam ?date {
  ?exam a ex:PhysicalExamination;
        dc:date ?date;
        ex:precedes ex:operation1 .
  ?op   a ex:SurgicalProcedure; dc:date ?opDT .
  FILTER NOT EXISTS {
    ?otherExam a ex:PhysicalExamination;
               ex:follows ?exam;
               ex:precedes ex:operation1
  } 
}