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JSYML
2008
84views more  JSYML 2008»
14 years 9 months ago
The modal logic of affine planes is not finitely axiomatisable
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...
Ian Hodkinson, Altaf Hussain
JSYML
2008
71views more  JSYML 2008»
14 years 9 months ago
Regular ultrafilters and finite square principles
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...
Juliette Kennedy, Saharon Shelah, Jouko A. Vä...
JSYML
2008
50views more  JSYML 2008»
14 years 9 months ago
Analytic and coanalytic families of almost disjoint functions
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...
Bart Kastermans, Juris Steprans, Yi Zhang 0008
95
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JSYML
2008
112views more  JSYML 2008»
14 years 9 months ago
On the structure of the Medvedev lattice
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...
Sebastiaan Terwijn
80
Voted
JSYML
2008
82views more  JSYML 2008»
14 years 9 months ago
The number of openly generated Boolean algebras
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 ...
Stefan Geschke, Saharon Shelah