XII: 42, 524-563, LNM 649 (1978)
HILLARD, Gérard
Exemples de normes en théorie descriptive des ensembles (
Descriptive set theory)
The situations described in this paper are special cases of
1104, where a coanalytic set $A$ was represented as the union of an increasing family $A_{\alpha}$ of analytic sets indexed by the countable ordinals, such that every analytic subset of $A$ is contained in some $A_{\alpha}$. The hypotheses of
1104 are not easy to check: they are shown here to include the classical Cantor derivation on the coanalytic space of countable compact sets, and a new example on the coanalytic space of all right continuous functions
Comment: The whole subject has been exposed anew in Chapter XXIV of Dellacherie-Meyer,
Probabilités et PotentielKeywords: Derivations (set-theoretic),
Kunen-Martin theoremNature: Original
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