Universal Proof Theory: Semi-analytic Rules and Uniform Interpolation
share
In [7] and [8], Iemhoff introduced a connection between the existence of a terminating sequent calculi of a certain kind and the uniform interpolation property of the super-intuitionistic logic that the calculus captures. In this paper, we will generalize this relationship to also cover the substructural setting on the one hand and a much more powerful class of rules on the other. The resulted relationship then provides a uniform method to establish uniform interpolation property for the logics FL_e, FL_ew, CFL_e, CFL_ew, IPC, CPC and their K and KD-type modal extensions. More interestingly though, on the negative side, we will show that no extension of FL_e can enjoy a certain natural type of terminating sequent calculus unless it has the uniform interpolation property. It excludes almost all super-intutionistic logics and the logics K4 and S4 from having such a reasonable calculus.
READ FULL TEXT