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 2025Show all

2 papers · 1 filter

math.LO2025

Variants of Łoś's Theorem

Toshimichi Usuba

We study Łoś's theorem in a choiceless context. We introduce some variants of Łoś's theorem. These variants seem weaker than Łoś's theorem, but we prove that these are equivalent t…

math.LO2025

Monotonicity of the ultrafilter number function

Toshimichi Usuba

We investigate whether the ultrafilter number function $κ \mapsto u (κ)$ on the cardinals is monotone, that is, whether $u (λ) \leq u (κ)$ holds for all…