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.

As cause we often specify an event the occurrence of which first guaranteed that of the effect. This notion is explicated in a framework of branching worlds in Sections I to V. VI and VII point out its close relations to the concept of an agent's bringing about an event. The topic of the last two sections is the distinction between causes and necessary circumstances. For this purpose conditionals are used, interpreted with respect to branching worlds without a similarity relation (...) between them. (shrink)

As cause we often specify an event the occurrence of which first guaranteed that of the effect. This notion is explicated in a framework of branching worlds in Sections I to V. VI and VII point out its close relations to the concept of an agent's bringing about an event. The topic of the last two sections is the distinction between causes and necessary circumstances. For this purpose conditionals are used, interpreted with respect to branching worlds without a similarity relation (...) between them. (shrink)

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.

Considering the growing need for formal counterparts of causal nexus (AI is desperately looking for a good one!) and thus trying to construct appropriate relations within a formal framework one faces the problem that the notion of “causal connection” is by no means explained with sufficient precision. How to overcome the resulting difficulties?