Causality is a concept which is sometimes claimed to be easy to illustrate, but hard to explain. It is not quite clear whether the former part of this claim is as obvious as the latter one. I will not present any specific theory of causation. Our aim is much less ambitious; to investigate the formal counterparts of causal relations between events, i.e. to propose a formal framework which enables us to construct metamathematical counterparts of causal relations between singular events. This (...) should be a good starting point to define formal counterparts for concepts like causal law, causal explanation and so on. (shrink)