  The asynchronous systems are the models of the asynchronous circuits from the
digital electrical engineering. An asynchronous system f is a multi-valued
function that assigns to each admissible input u a set f(u) of possible states
x in f(u). A special case of asynchronous system consists in the existence of a
Boolean function \Upsilon such that for any u and any x in f(u), a certain
equation involving \Upsilon is fulfilled. Then \Upsilon is called the generator
function of f (Moisil used the terminology of network function) and we say that
f is generated by \Upsilon. The systems that have a generator function are
called regular.
  Our purpose is to continue the study of the generation of the asynchronous
systems that was started in [2], [3].
