Generalized projections of Borel and analytic sets
Balcerzak, Marek
Colloquium Mathematicae, Tome 70 (1996), p. 47-53 / Harvested from The Polish Digital Mathematics Library
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For a σ-ideal I of sets in a Polish space X and for A ⊆ X2, we consider the generalized projection (A) of A given by (A) = x ∈ X: Ax ∉ I, where Ax =y ∈ X: 〈x,y〉∈ A. We study the behaviour of with respect to Borel and analytic sets in the case when I is a ∑20-supported σ-ideal. In particular, we give an alternative proof of the recent result of Kechris showing that [∑11(X2)]=∑11(X) for a wide class of ∑20-supported σ-ideals.

Publié le : 1996-01-01
EUDML-ID : urn:eudml:doc:210426 
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     author = {Marek Balcerzak},
     title = {Generalized projections of Borel and analytic sets},
     journal = {Colloquium Mathematicae},
     volume = {70},
     year = {1996},
     pages = {47-53},
     zbl = {0864.54030},
     language = {en},
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Balcerzak, Marek. Generalized projections of Borel and analytic sets. Colloquium Mathematicae, Tome 70 (1996) pp. 47-53. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-cmv71i1p47bwm/

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