Toshimichi Usuba

activity

20132025

most citedChoiceless Löwenheim-Skolem property and uniform definability of grounds

1 citations · 3 across the 15 of their papers we have counts for

collaborators

Showing 2017Show all

2 papers · 1 filter

math.LO2017

$G_{δ}$ -topology and compact cardinals

Toshimichi Usuba

For a topological space $X$ , let $X_{δ}$ be the space $X$ with $G_{δ}$ -topology of $X$ . For an uncountable cardinal $κ$ , we prove that the following are equivalent: (1) $κ$ is $ω_{1}$ -st…

math.LO2017

The downward directed grounds hypothesis and very large cardinals

Toshimichi Usuba

A transitive model $M$ of ZFC is called a ground if the universe $V$ is a set forcing extension of $M$ . We show that the grounds of $V$ are downward set-directed. Consequently, we…

Gδ​-topology and compact cardinals

The downward directed grounds hypothesis and very large cardinals

$G_{δ}$ -topology and compact cardinals