We consider a modal language for affine planes, with two sorts of formulas (for points and lines) and three modal boxes. To evaluate formulas, we regard an affine plane as a Kripke...
We show that many singular cardinals above a strongly compact cardinal have regular ultrafilters D that violate the finite square principle fin ,D introduced in [3]. For such ult...
If F N N is an analytic family of pairwise eventually different functions then the following strong maximality condition fails: For any countable H N N, no member of which is cov...
We investigate the structure of the Medvedev lattice as a partial order. We prove that every interval in the lattice is either finite, in which case it is isomorphic to a finite B...
This article is devoted to two different generalizations of projective Boolean algebras: openly generated Boolean algebras and tightly -filtered Boolean algebras. We show that for ...