changeAttributes(ident uid, ident id, ident taskId, double maxPoints) {
  assume exists /account[uid]/examiner[id];
 
  assume exists /exam[id]/task[taskId]; # implies the existence of the exam
 
  assume maxPoints >= 0;
  assume /exam[id]/participant[x]/result[taskId]/points <= maxPoints;
 
  update /exam[id]/task[taskId]/maxPoints maxPoints;
}