:: deftheorem defines [: FILTER_1:def 7 :
for L1, L2 being non empty LattStr holds [:L1,L2:] = LattStr(# [: the carrier of L1, the carrier of L2:],|: the L_join of L1, the L_join of L2:|,|: the L_meet of L1, the L_meet of L2:| #);