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Delta_1-definability of the non-stationary ideal

Presented by: 
L Zdomskyy Universität Wien
Friday 28th August 2015 - 11:30 to 12:30
INI Seminar Room 1
The talk will be devoted to the proof of the fact that assuming $V = L$, for every successor cardinal $\kappa$ there exists a GCH and cardinal preserving forcing poset $P \in L$ such that in $L^P$ the ideal of all non-stationary subsets of $\kappa$ is $\Delta_1$-definable over $H(\kappa^+)$. We shall also discuss the situation for limit $\kappa$.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons