  The conductance ${\cal G}$ of an Aharonov-Bohm interferometer (ABI), with a
strongly correlated quantum dot on one arm, is expressed in terms of the dot
Green function, $G_{dd}$, the magnetic flux $\phi$ and the non-interacting
parameters of the ABI. We show that one can extract $G_{dd}$ from the observed
oscillations of ${\cal G}$ with $\phi$, for both closed and open ABI's. In the
latter case, the phase shift $\beta$ deduced from ${\cal G} \approx
A+B\cos(\phi+\beta)$ depends strongly on the ABI's parameters, and usually
$\beta \ne \pi/2$. These parameters may also reduce the Kondo temperature,
eliminating the Kondo behavior.
