The incidence propagation method

Incidence calculus is a probabilistic logic developed from propositional logic which associates probabilities with sets of possible worlds rather than with formulae directly. The probability of a formula is defined as the probability of the set of possible worlds in which this formula is true. This set of possible worlds is named as the incidence set of this formula. So the task of calculating probabilities of formulae relies on the task of obtaining incidence sets for formulae. In this paper, we present an approach for manipulating incidences in extended incidence calculus in the situation that, the language set is large. We will show how to decompose this large set into small, but coherent sets and then how to propagate incidences among these sets. In this way incidence sets can be calculated efficiently