TITLE: Theory of addition and a predicate that recognizes powers of 2
QUESTION [5 upvotes]: What is the complexity of the theory of addition (Presburger arithmetic) augmented by a unary predicate that recognizes powers of 2?

REPLY [7 votes]: The theory of the natural numbers with addition and $x\mapsto 2^x$ is decidable.
One reference is the Cherlin-Point paper "On extensions of Presburger arithmetic".
It can be found on Francoise Point's webpage:
http://www.logique.jussieu.fr/~point/papiers/cherlin_point86.pdf