For arbitrary families
A and B of subsets of R let
C(A,B)=
{f| f: R-->R and the image
f[A] is in B for every A in A}
and
(A,B)=
{f| f: R-->R and the inverse image
(B)
is in A for every B in B}.
A family F of real
functions is characterizable by images (preimages) of sets if
F=C(A,B)
(F=(A,B), respectively)
for some families A and B.
We study which of classes of Darboux like functions can be
characterized in this way. Moreover, we prove that the class of all
Sierpinski-Zygmund functions can be characterized by neither
images nor preimages of sets.
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Last modified September 10, 1998.