  Mesoscopic Aharonov-Bohm interferometers have been used in attempts to
measure the transmission phase of a quantum dot which is placed on one arm of
the interferometer. Here we review theoretical results for the conductance
through such interferometers, for both the closed (two-terminal) and open
(multi-terminal) cases. In addition to earlier results for the Coulomb blockade
regime, we present new results for the strongly correlated Kondo regime, and
test the consistency of the two-slit analysis of some data from open
interferometer experiments.
