Erratum to: Abductive Reasoning in Explanation Problems of an Observed Effect

Theorem 1 on p. 339 should read as follows:

Theorem 1. A formula F ⁰ of the language ${{L}_{S}}$ is contradictory if F ⁰ is derivable in ${{\mathbb{C}}_{\alpha }}$. The converse is true if, in the domain of action of each base from F ⁰, the union of the conjuncts of type → vertices does not contain contrary literals.