theorem Th133:
  Union <*X*> = X & meet <*X*> = X
proof
  thus Union <*X*> = union rng <*X*>
    .= union {X} by FINSEQ_1:38
    .= X by ZFMISC_1:25;
  thus meet <*X*> = meet {X} by FINSEQ_1:38
    .= X by SETFAM_1:10;
end;
