Lusin-Sierpiński index for the internal sets
AbstractWe prove that there exists a function f which reduces a given subset P of an internal set X of an ω1 saturated nonstandard universe to the set WF of well-founded trees possessing properties similar to those possessed by the standard part map. We use f to define the Lusin-Sierpiński index of points in X, and prove the basic properties of that index using the classical properties of the Lusin-Sierpiński index. An example of a but not set is given.
2020 ◽
Vol 23
(3)
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pp. 227-252
2012 ◽
Vol 132
(11)
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pp. 420-424
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1980 ◽
Vol 45
(7)
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pp. 1937-1939
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