arXiv subjects
Publications and source records attributed to Wolfgang Wohofsky.
We show in ZFC that there is no set of reals of size continuum which can be translated away from every set in the Marczewski ideal. We also show that in the Cohen model, every set with this property is countable.
Using a game characterization of distributivity, we show that base matrices for $\mathcal{P}(ω)/\text{fin}$ of regular height larger than $\mathfrak{h}$ necessarily have maximal branches which are not cofinal.
We construct a model in which there exists a distributivity matrix of regular height $λ$ larger than $\mathfrak{h}$; both $λ= \mathfrak{c}$ and $λ< \mathfrak{c}$ are possible. A distributivity matrix is a refining system of mad families without common refinement. Of particular interest in our proof is the preservation of $\mathcal{B}$-Canjarness.
We investigate generalizations of the topology of the higher Cantor space on $2^κ$, based on arbitrary ideals rather than the bounded ideal on $κ$. Our main focus is on the topology induced by the nonstationary ideal, and we call this topology the nonstationary topology, or also the Edinburgh topology on $2^κ$. It may be of independent interest that as a side result, we show $κ$-Silver forcing to satisfy a strong form of Axiom $A$ not only if $κ$ is inaccessible (which is well-known), but also under the assumption $\diamondsuit_κ$.
We prove that any suitable generalization of Laver forcing to the space $ κ^κ$, for uncountable regular $κ$, necessarily adds a Cohen $κ$-real. We also study a dichotomy and an ideal naturally related to generalized Laver forcing. Using this dichotomy, we prove the following stronger result: if $ κ^{<κ}=κ$, then every $<κ$-distributive tree forcing on $κ^κ$ adding a dominating $κ$-real which is the image of the generic under a continuous function in the ground model, adds a Cohen $κ$-real. This is a contribution to the study of generalized Baire spaces and answers a question from arXiv:1611.08140
We show that the cofinalities of both the Miller ideal m^0 (the sigma-ideal naturally related to Miller forcing) and the Laver ideal ell^0 (related to Laver forcing) are larger than the size of the continuum in ZFC.
We show that it is consistent that the Borel Conjecture and the dual Borel Conjecture hold simultaneously.
This note gives an informal overview of the proof in our paper "Borel Conjecture and Dual Borel Conjecture", see arXiv:1105.0823.