  We define and axiomatize approximate exclusion atoms in the team semantic
setting. A team is a set of assignments, which can be seen as a mathematical
model of a uni-relational database, and we say that an approximate exclusion
atom is satisfied in a team if the corresponding usual exclusion atom is
satisfied in a large enough subteam. We consider the implication problem for
approximate exclusion atoms and show that it is axiomatizable for consequences
with a degree of approximation that is not too large. We prove the completeness
theorem for usual exclusion atoms, which is currently missing from the
literature, and generalize it to approximate exclusion atoms. We also provide a
polynomial time algorithm for the implication problems. The results also apply
to exclusion dependencies in database theory.
