# E. Thuemmel, J. Verner: Exponent & Generalized Grigorieff Forcing

Wednesday, January 8, 2014, 11:00
Prague – Zitna, seminar room 3rd floor

Speaker: E. Thuemmel, J. Verner

Title: Exponent & Generalized Grigorieff Forcing

Abstract:

M. Hrušák asked whether every tall Borel (analytic) ideal contains a tall F-sigma ideal. E. Thuemmel gave a partial answer showing that every tall analytic ideal I contains an F-sigma ideal which is tall when restricted to some I-positive set. In the lecture he showed two proofs of this fact.

J. Verner talked about Grigorieff forcing generalized to an uncountable setting. This was based on the paper by R. Honzík and himself: A lifting argument for generalized Gregorieff forcing (to appear in NDJFL).

Notes from the seminar are available.