Using complementary priors to eliminate
explaining away
A “complementary” prior is defined
as one that exactly cancels the
correlations created by explaining
away. So the posterior factors.
Under what conditions do
complementary priors exist?
Complementary priors do not
exist in general:
 Parameter counting shows that
complementary priors cannot exist
if the relationship between the
hidden variables and the data is
defined by a separate conditional
probability table for each hidden
configuration.
hidden variables
hidden variables
prior
hidden variables
likelihood
          data