% Elements
member(true).
member(false).
members([false,true]).

% Ordering relation
leq(false, true).
leq(X, X).

% Supremum and infimum
bot(false).
top(true).

% Binary operations
and_bool(true, true, true) :- !.
and_bool(_, _, false).
or_bool(false, false, false) :- !.
or_bool(_, _, true).