Asger Tornquist

activity

20072025

most citedOrbit Equivalence and actions of F_n

27 citations · 37 across the 13 of their papers we have counts for

collaborators

15 papers

math.LO2025

The happy coexistence of mad families and Laver measurability

Asger Tornquist, David Schrittesser

Let $x$ denote a Laver real over $L$ . We prove that in $L [x]$ there is a $Π_{1}^{1}$ infinite mad family. Since $Π_{1}^{1}$ and $Σ_{2}^{1}$ sets are Laver measurable in $L [x]$ , this shows that…

math.LO2020★ 1 cited

The Ramsey property and higher dimensional mad families

David Schrittesser, Asger Törnquist

We prove that under a principle of Ramsey regularity there are no infinite maximal almost disjoint families with respect to the transfinitely iterated Fréchet ideals. The results o…

math.GR2019

A short proof of Thoma's theorem on type I groups

Fabio Elio Tonti, Asger Törnquist

In the theory of unitary group representations, a group is called type I if all factor representations are of type I, and by a celebrated theorem of James Glimm [Gli61b], the type…

math.LO2016★ 1 cited

Definable maximal cofinitary groups

Vera Fischer, Sy David Friedman, Asger Törnquist

Using countable support iteration of $S$ -proper posets, for some appropriate stationary set $S$ , we obtain a generic extension of the constructible universe, in which $\mathfrak{b}…

math.LO2015★ 3 cited

Definable maximal discrete sets in forcing extensions

David Schrittesser, Asger Törnquist

Let $R$ be a $Σ_{1}^{1}$ binary relation, and recall that a set $A$ is $R$ -discrete if no two elements of $A$ are related by $R$ . We show that in the Sacks a…

math.LO2015

Definability and almost disjoint families

Asger Tornquist

We show that there are no infinite maximal almost disjoint ("mad") families in Solovay's model, thus solving a long-standing problem posed by A.D.R. Mathias in 1967. We also give a…