theorem Th11:
  L is 1_Lattice implies Top L in H
proof
  assume L is 1_Lattice;
  then reconsider L as 1_Lattice;
  consider p being Element of L such that
A1: p in H by SUBSET_1:4;
  p [= Top L by LATTICES:19;
  hence thesis by A1,Th9;
end;
