Undecidabiliity for the additive AIA fragment of the theory of normed spaces.

Authors: R.D. Arthan
Subjects: Logic
link: http://arxiv.org/abs/1002.1381
Abstract

An AIA formula is one of the form 'A implies B' where A and B are purely
universal. Up to a simple reduction AIA formula are both EA and AE. In an
earlier paper Solovay, Harrison and I proved the undecidability of validity for
the AIA fragment of a two-sorted first-order language for normed vector spaces.
In this note we find that validity remains undecidable for AIA sentences in the
additive sublanguage, i.e., when multiplication is disallowed.