5 papers · 1 filter
The ultrafilter and almost disjointness numbers
Osvaldo Guzman, Damjan Kalajdzievski
We prove that every MAD family can be destroyed by a proper forcing that preserves -points. With this result, we prove that it is consistent that $ω_{1}=\mathfrak{u}<\mathfrak{a…
Splitting chains, tunnels and twisted sums
Félix Cabello Sánchez, Antonio Avilés, Piotr Borodulin-Nadzieja +2
We study splitting chains in , that is, families of subsets of which are linearly ordered by and which are splitting. We prove that their existenc…
P-points, MAD families and Cardinal Invariants
Osvaldo Guzman
This is the Ph.D. thesis of the author, which was written under the supervision of Michael Hrušák at UNAM. The main contributions of this thesis are the following: There is a -R…
On \emph{-}weakly universal functions
Osvaldo Guzman
A function is called \emph{-weakly universal }if for every function $F:\left[ ω_{1}\right] ^{2}\longrightarrowω…
There is a -Ramsey \textsf{MAD} family
Osvaldo Guzman
We answer an old question of Michael Hrušák by constructing a -Ramsey \textsf{MAD} family without the need of any additional axioms beyond We also prove that eve…