4 papers
Are scales Fréchet?
Raul Figueroa-Sierra, Osvaldo Guzmán, Michael Hrušák +1
We continue the study of Dow spaces of a -scale, originally introduced by Alan Dow in "-Weight and the Fréchet-Urysohn property" (Topology and its Applications,…
Diamonds on trees
Osvaldo Guzmán, Carlos López-Callejas
We generalize the diamond principle and its variants using the notion of stationarity in trees introduced by Brodsky in [Brodsky, A. M., A theory of stationary trees and the balanc…
Properties of Laver forcing associated with a co-ideal expressed via the Katetov order
Francisco Santiago Nieto-de la Rosa, Osvaldo Guzmán, Osvaldo Guzmán +1
We study variants of classical Laver forcing defined from co-ideals and analyze their combinatorial properties in terms of the Katětov order. In particular, we give a Katětov-theor…
Shelah Ultrafilters
Emmanuel Balderas, David Chodounský, Osvaldo Guzmán
In this paper, we study a special type of ultrafilter which we call Shelah ultrafilter. We show that it is possible to add a Shelah ultrafilter using a special forcing notion. We a…