  The Beth Definability Property holds for an algebraizable logic if and only
if every epimorphism in the corresponding category of algebras is surjective.
Using this technique, Urquhart in 1999 showed that the Beth Definability
Property fails for a wide class of relevant logics, including T, E, and R.
However, the counterexample for those logics does not extend to the algebraic
counterpart of the super relevant logic KR, the so-called Boolean monoids.
Following a suggestion of Urquhart, we use modular lattices constructed by
Freese to show that epimorphisms need not be surjective in a wide class of
relation algebras. This class includes the Boolean monoids, and thus the Beth
Definability Property fails for KR.
