  A database D may be inconsistent wrt a given set IC of integrity constraints.
Consistent Query Answering (CQA) is the problem of computing from D the answers
to a query that are consistent wrt IC . Consistent answers are invariant under
all the repairs of D, i.e. the consistent instances that minimally depart from
D. Three classes of repair have been considered in the literature: those that
minimize set-theoretically the set of tuples in the symmetric difference; those
that minimize the changes of attribute values, and those that minimize the
cardinality of the set of tuples in the symmetric difference. The latter class
has not been systematically investigated. In this paper we obtain algorithmic
and complexity theoretic results for CQA under this cardinality-based repair
semantics. We do this in the usual, static setting, but also in a dynamic
framework where a consistent database is affected by a sequence of updates,
which may make it inconsistent. We also establish comparative results with the
other two kinds of repairs in the dynamic case.
