Part 1 describes Stanisaw Jakowski's concept of defining some often used con ditionals, namely, factorial, ewfficient and definitive implications.Part 2 contains the results strictly connected with the theory of the above implications.

Classical logic, intuitionism, relevant logics and many other systems try to express implication as an entailment. The Jaskowski system Qf describes implication in connection with causality. Syntactic properties of Qf have been examined by Pieczkowski [4], [5]. The semantic characterization of Qf is the aim of this paper.