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math.LO2017
On Kuratowski partitions
Ryszard Frankiewicz, Joanna Jureczko
In 1935 K. Kuratowski posed the problem whether a function f:X ! Y , (X is completely metrizable and Y is metrizable), with the property that a preimage of each open has the Baire…
math.LO2017
A short mathematical proof of Frankiewicz - Kunen theorem
Ryszard Frankiewicz, Joanna Jureczko
In this paper there is proved without any metamathematical techniques that the existence of precipitous ideals immediately follows from Kuratowski partitions.
math.LO2017
On Kuratowski partitions in the Marczewski structure and Ellentuck topology
Ryszard Frankiewicz, Joanna Jureczko
We show that large sets in Ellentuck topology (i.e. sets which are not nowhere Ramsey) do not admit Kuratowski's partition. The similar result is true for the Sacks real forcing.