It is known that the set of intermediate propositional logics
that can prove their own completeness theorems is exactly those
which prove every instance of the principle of testability,
¬ϕ ∨ ¬¬ϕ. Such logics are called
reflexive. This paper classifies reflexive intermediate logics in
the first-order case: a first-order logic is reflexive if and only
if it proves every instance of the principle of double negation
shift and the metatheory created from it proves every instance of
the principle of testability.
@article{1199649902,
author = {Carter, Nathan C.},
title = {Reflexive Intermediate First-Order Logics},
journal = {Notre Dame J. Formal Logic},
volume = {49},
number = {1},
year = {2008},
pages = { 75-95},
language = {en},
url = {http://dml.mathdoc.fr/item/1199649902}
}
Carter, Nathan C. Reflexive Intermediate First-Order Logics. Notre Dame J. Formal Logic, Tome 49 (2008) no. 1, pp. 75-95. http://gdmltest.u-ga.fr/item/1199649902/