Regularity properties of definable sets of reals (Q1069930)

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scientific article; zbMATH DE number 3933056
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Regularity properties of definable sets of reals
scientific article; zbMATH DE number 3933056

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    Regularity properties of definable sets of reals (English)
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    1985
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    Various desirable properties of sets of reals which follow from the axiom of determinateness have been shown to be consistent with ZF. This paper is a further contribution to this subject improving results obtained by R. M. Solovay and S. Shelah. The main theorem states that - assuming the existence of a standard model of ZF - there is a standard model of ZFC in which (i) every set of reals definable from ordinals and reals as parameters has the property of Baire and contains a perfect set or is well-ordered with order type \(\leq \omega_ 1\), and (ii) every ordinal- definable set of reals is Lebesgue-measurable and is Ramsey (and some additional properties hold). The author's main tool is a new concept of forcing with topologically ordered sets satisfying a ''lower bound property''. (The papers by \textit{J. Raisonnier} and \textit{S. Shelah} to which the author refers have been published meanwhile in Isr. J. Math. 48 (1984), pp. 48-56 and pp. 1-47 resp.)
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    ordinal definability
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    Lebesgue measurability
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    Baire property
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    perfect set theorem
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    standard model of ZFC
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    forcing with topologically ordered sets
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