for L1, L2 being Lattice
for p1, q1 being Element of L1
for p2, q2 being Element of L2 st L1 is 01_Lattice & L2 is 01_Lattice holds
( ( p1 is_a_pseudocomplement_of q1 & p2 is_a_pseudocomplement_of q2 ) iff [p1,p2] is_a_pseudocomplement_of [q1,q2] )