Cyclic Proofs for iGL via Corecursion

Abstract: Daniyar Shamkanov proved that three distinct systems of sequent calculi for GL are equivalent. These systems consist in one with finite proofs, another with ill-founded proofs and the last one with cyclic proofs. The main tool used for proving the equivalence is corecursion. In this project, we prove the equivalence between a finitary sequent calculus for iGL and a cyclic calculus, using also coinductive methods.