
theorem Th2:
  for X,Y being TopSpace, A being Subset of X st [#]X c= [#]Y holds
  incl(X,Y).:A = A
proof
  let X,Y be TopSpace, A be Subset of X;
  assume [#]X c= [#]Y;
  hence incl(X,Y).:A = id([#]X).:A by YELLOW_9:def 1
    .= A by FUNCT_1:92;
end;
