reserve x,X,X2,Y,Y2 for set;
reserve GX for non empty TopSpace;
reserve A2,B2 for Subset of GX;
reserve B for Subset of GX;

theorem Th19:
  {}(GX) is a_union_of_components of GX
proof
  thus ex F being Subset-Family of GX st (for B being Subset of GX st B in F
  holds B is a_component) & {}(GX) = union F by Lm1;
end;
