let C be complete Lattice; ( C is 1_Lattice & Top C = "\/" the carrier of C,C )
set j = "\/" the carrier of C,C;
A1:
now let a be
Element of
C;
( ("\/" the carrier of C,C) "\/" a = "\/" the carrier of C,C & a "\/" ("\/" the carrier of C,C) = "\/" the carrier of C,C )A2:
"\/" the
carrier of
C,
C [= ("\/" the carrier of C,C) "\/" a
by LATTICES:22;
A3:
("\/" the carrier of C,C) "\/" a [= "\/" the
carrier of
C,
C
by Th38;
hence
("\/" the carrier of C,C) "\/" a = "\/" the
carrier of
C,
C
by A2, LATTICES:26;
a "\/" ("\/" the carrier of C,C) = "\/" the carrier of C,Cthus
a "\/" ("\/" the carrier of C,C) = "\/" the
carrier of
C,
C
by A2, A3, LATTICES:26;
verum end;
then
C is upper-bounded
by LATTICES:def 14;
hence
( C is 1_Lattice & Top C = "\/" the carrier of C,C )
by A1, LATTICES:def 17; verum