Note on Deduction Theorems in contraction‐free logics
Karel Chvalovský, Petr Cintula · Mathematical logic quarterly · 2012
Abstract This paper provides a finer analysis of the well‐known form of the Local Deduction Theorem in contraction‐free logics (understood as Tarski‐style finitary structural consequence relations). An infinite hierarchy of its natural strengthenings is introduced and studied. The main results are the separation of its initial four members and the subsequent collapse of the hierarchy.