theorem Th72:
  the carrier of latt (L,P) = P & the L_join of latt (L,P) = (the
  L_join of L)||P & the L_meet of latt (L,P) = (the L_meet of L)||P
proof
  ex o1, o2 st o1 = join(L)||P & o2 = met(L)||P & latt (L,P) = LattStr (#P
    , o1, o2#) by Def14;
  hence thesis;
end;
