The exterior square
L-function attached to an automorphic cuspidal representation of GL2n has a pole if
and only if a certain period integral does not vanish on the space of the
representation. We conjecture, in the “if” direction, a similar result is true for
representations of GL2(D), where D is a division algebra. We prove a partial result
which provides evidence for the conjecture. The proof is based on a relative trace
formula.