(VAR x y z)
(RULES
not(not(x)) -> x
not(or(x,y)) -> and(not(x),not(y))
not(and(x,y)) -> or(not(x),not(y))
and(x,or(y,z)) -> or(and(x,y),and(x,z))
and(or(y,z),x) -> or(and(x,y),and(x,z))
)

(COMMENT Example 12 in \cite{D33})