logical operator. The extended system, called NEL is defined in the formalism of the calculus
of structures, which is a generalisation of the sequent calculus and provides a more refined
analysis of proofs. We should then be able to extend the range of applications of MEL, L by
modelling a broad notion of sequentiality and providing new properties of proofs. We show
some proof theoretical results: decomposition and cut elimination. The new operator …