two dual theories have the same global symmetries and the ’t Hooft anomaly matching conditions for these symmetries are satisfied.

[2.]{} The two theories have the same moduli space of vacua. These are obtained by giving expectation values to the first components of chiral superfields.

[3.]{} The equivalence is preserved under deformations of the theories by the $F$-components of chiral operators. In particular the moduli spaces and chiral rings agree as a function of these deformations.

It is important to stress that in every one of these tests the classical theories are different and only the quantum theories become equivalent. There is also a crucial difference in the physical interpretation of the deformations of the two theories along the moduli space and by the chiral operators. Often, when one theory is Higgsed and becomes weaker, its dual is confining and becomes stronger. This is one of the reasons for interpreting the relation between these theories as electric-magnetic duality.

The last two tests above are closely related. The rings of chiral operators can be thought of as functions on the moduli space ${\CM}_0$. Hence, one might think that test two above implies test three. However, such a relation is not always 