  Grishin's generalization of Lambek's Syntactic Calculus combines a
non-commutative multiplicative conjunction and its residuals (product, left and
right division) with a dual family: multiplicative disjunction, right and left
difference. Interaction between these two families takes the form of linear
distributivity principles. We study proof nets for the Lambek-Grishin calculus
and the correspondence between these nets and unfocused and focused versions of
its sequent calculus.
