reserve T for TopSpace,
  A, B for Subset of T;

theorem :: Remark:: Corollary to Theorem 7
  A is condensed iff Int A is regular_open & Cl A is regular_closed &
  Border A is empty
proof
  thus A is condensed implies Int A is regular_open & Cl A is regular_closed &
  Border A is empty by Th22;
  assume that
A1: Int A is regular_open and
A2: Cl A is regular_closed and
A3: Border A is empty;
A4: A is subcondensed by A2,A3,Th23;
  A is supercondensed by A1,A3,Th22;
  hence thesis by A4;
end;
