reserve A, B for non empty set,
  A1, A2, A3 for non empty Subset of A;
reserve X for TopSpace;
reserve X for non empty TopSpace;
reserve X1, X2 for non empty SubSpace of X;
reserve X0, X1, X2, Y1, Y2 for non empty SubSpace of X;

theorem
  X0 meet X0 = the TopStruct of X0
proof
A1: X0 is SubSpace of X0 by TSEP_1:2;
  then X0 meets X0 by Th17;
  hence thesis by A1,TSEP_1:28;
end;
