collaborators

3 papers

math.LO2026

A unique -point and infinitely many near-coherence classes of ultrafilters

Lorenz Halbeisen, Silvan Horvath, Saharon Shelah

We show that in the model obtained by iteratively pseudo-intersecting a Ramsey ultrafilter via a length- countable support iteration of restricted Mathias forcing over a grou…

math.NT2025

Integer triangles with a rational ratio of circumcircle radius to excircle radius

Lorenz Halbeisen, Norbert Hungerbühler, Arman Shamsi Zargar

We consider the problem of finding integer triangles with a positive rational, where and are the radii of the circumcircle and an excircle, respectively. We show that…

math.LO2025

There may be exactly -points

Lorenz Halbeisen, Silvan Horvath, Tan Özalp

We generalize the main result of arXiv:2505.17960 and show the consistency of the statement ``There are exactly -points up to isomorphism" for any finite . Furthermore, w…