let R be CLatAugmentation of L; R is join-commutative
OrthoLattStr(# the carrier of L, the L_join of L, the L_meet of L, the Compl of L #) = OrthoLattStr(# the carrier of R, the L_join of R, the L_meet of R, the Compl of R #)
by Def12;
then
LattStr(# the carrier of L, the L_join of L, the L_meet of L #) = LattStr(# the carrier of R, the L_join of R, the L_meet of R #)
;
hence
R is join-commutative
by Th9; verum