An interpretation of S 2 1 in Σ 1 b -NIA. Ferreira, Gilda; Oitavem, Isabel — 2006 Portugaliae Mathematica. Nova Série
Elementary Proof of Strong Normalization for Atomic F Fernando Ferreira; Gilda Ferreira — 2016 Bulletin of the Section of Logic We give an elementary proof (in the sense that it is formalizable in Peano arithmetic) of the strong normalization of the atomic polymorphic calculus Fat (a predicative restriction of Girard’s system F).