On the Complexity of the Quantified Bit-Vector Arithmetic with Binary Encoding

We study the precise computational complexity of deciding satisfiability of first-order quantified formulas over the theory of fixed-size bit-vectors with binary-encoded bit-widths and constants. This problem is known to be in EXPSPACE and to be NEXPTIME-hard. We show that this problem is complete for the complexity class AEXP(poly) -- the class of problems decidable by an alternating Turing machine using exponential time, but only a polynomial number of alternations between existential and universal states.