
theorem Th4:
  for C being FormalContext for D being Subset of ConceptLattice(C)
holds "/\"(D,ConceptLattice(C)) is FormalConcept of C & "\/"(D,ConceptLattice(C
  )) is FormalConcept of C
proof
  let C be FormalContext;
  let D be Subset of ConceptLattice(C);
  ConceptLattice(C) = LattStr(#B-carrier(C),B-join(C),B-meet(C)#) by
CONLAT_1:def 20;
  hence thesis by CONLAT_1:31;
end;
