let L be non empty LattStr ; ( L = RealFunc_Lattice A implies ( L is join-commutative & L is join-associative & L is meet-absorbing & L is meet-commutative & L is meet-associative & L is join-absorbing ) )
assume Z:
L = RealFunc_Lattice A
; ( L is join-commutative & L is join-associative & L is meet-absorbing & L is meet-commutative & L is meet-associative & L is join-absorbing )
thus
for p, q being Element of L holds p "\/" q = q "\/" p
by Th20, Z; LATTICES:def 4 ( L is join-associative & L is meet-absorbing & L is meet-commutative & L is meet-associative & L is join-absorbing )
thus
for p, q, r being Element of L holds p "\/" (q "\/" r) = (p "\/" q) "\/" r
by Th22, Z; LATTICES:def 5 ( L is meet-absorbing & L is meet-commutative & L is meet-associative & L is join-absorbing )
thus
for p, q being Element of L holds (p "/\" q) "\/" q = q
by Th26, Z; LATTICES:def 8 ( L is meet-commutative & L is meet-associative & L is join-absorbing )
thus
for p, q being Element of L holds p "/\" q = q "/\" p
by Th21, Z; LATTICES:def 6 ( L is meet-associative & L is join-absorbing )
thus
for p, q, r being Element of L holds p "/\" (q "/\" r) = (p "/\" q) "/\" r
by Th23, Z; LATTICES:def 7 L is join-absorbing
thus
for p, q being Element of L holds p "/\" (p "\/" q) = p
by Th28, Z; LATTICES:def 9 verum