  In probabilistic logic entailments, even moderate size problems can yield
linear constraint systems with so many variables that exact methods are
impractical. This difficulty can be remedied in many cases of interest by
introducing a three valued logic (true, false, and "don't care"). The
three-valued approach allows the construction of "compressed" constraint
systems which have the same solution sets as their two-valued counterparts, but
which may involve dramatically fewer variables. Techniques to calculate point
estimates for the posterior probabilities of entailed sentences are discussed.

Artificial Intelligence