On several classes of sets II

Summary In this paper several classes of sets are stuided. It is shown that these classes are incomparable under the relation inclusion. If the setA is in one of our classes we examine whether it must follow thatAK is in the same class, forK a finite or countable set. We also discuss which functions preserve the various classes under consideration.The research on this paper was supported by the Foundation for Scientific Work of the Republic of Bosnia and HerzegovinaDedicated to the memory of Alexander Ostrowski on the occasion of the 100th anniversary of his birth