Logic Seminar
Philipp Hieronymi
UIUC
Expansions of the ordered additive group of real numbers by two discrete subgroups
Abstract: Let R be the set of real numbers and let Z be the set of integers. The theory (R,<,+,Z,aZ) is decidable if a is quadratic. If a is the golden ratio, (R,<,+,Z,aZ) defines multiplication by a. The results are established by using the Ostrowski representation of a real number based on the continued fraction expansions of a to define the above structures in monadic second order logic of one successor.
Tuesday March 18, 2014 at 4:00 PM in SEO 427