 For every belief base \(A\), there is a belief set \(\Cn(A)\) that represents the beliefs held according to \(A\). On the other hand, one and the same belief set can be represented by different belief bases. In this sense, belief bases have more expressive power than belief sets. As an example, the two belief bases \(\{p, q\}\) and \(\{p, p \leftrightarrow q\}\) have the same logical closure. They are therefore statically equivalent, in the sense of representing the same beliefs. On the other hand, the following example shows that they are not dynamically equivalent in the sense of behaving in the same way under operations of change. They can be taken to represent different ways of holding the same beliefs.