Structural Interactions and Absorption of Structural Rules in BI Sequent   Calculus
  Development of a contraction-free BI sequent calculus, be it in the sense of G3i or G4i, has not been successful in literature. We address the open problem by presenting such a sequent system. In fact our calculus involves no structural rules. 
Ryuta Arisaka (INRIA Saclay - Ile de France)
cs.LO