On extendability to F_σ ideals

2021/06/24 by Kwela, Adam
#03E15 #40A05 #54A20 #54H05 #FOS: Mathematics #Logic (math.LO) #Primary: 03E05 #Secondary: 26A03

paper · doi:10.48550/arxiv.2106.13053

Abstract

Answering in negative a question of M. Hrušák, we construct a Borel ideal not extendable to any F_σ ideal and such that it is not Katětov above the ideal conv.

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