PROPERTIES OF BOREL SETS

This article the properties of sets F and G   , which are Borel sets,
in topological spaces were studied and the following results were obtained:
a) Preimage of the set F (resp. G ) under the continuous mapping is also the set
F (resp. G );
b) The image of the set G under the continuous mapping is not the set G ;
c) The image of the set G under the open mapping is not the set G ;
d) The sets F and G are preserved under the Cartesian product.