
theorem
  for C being strict FormalContext for CP being strict FormalConcept of
  C holds (CP.:).: = CP
proof
  let C be strict FormalContext;
  let CP be strict FormalConcept of C;
A1: the Intent of (CP.:).: = the Extent of CP.: by Def8
    .= the Intent of CP by Def8;
  the Extent of (CP.:).: = the Intent of CP.: by Def8
    .= the Extent of CP by Def8;
  hence thesis by A1;
end;
